EXECUTIVE OFFICE

FIG. 2. Mercury spectrum.

The intensity of the monochromatic light is measured by aphotomultiplier tube with another dc amplifier. Its output is fedto the vertical deflectors of the cathode-ray tube. In this case,the energy distribution of the spectrum is indicated on the screen.

The spectrum of a germicidal lamp was measured by the gratingspectrometer5 with the said equipment. The result obtained isshown in Fig. 2. The dispersion of the spectrometer is constantat all wavelengths because a grating is used for dispersion.

I W. E. Deal, W. Bradshaw, and F. A. Matsen, J. Chem. Phys. 16, 638(1948); G. W. Bethke, J. Opt. Soc. Am. 50, 1Q54 (1960).

2 P. J. Wheatley, E. R. Vincent, D. L. Rotenberg, and G. R. Cowan, J.Opt. Soc. Am. 41, 665 (1951).

3 B. W. Bullock and S. Silverman, J. Opt. Soc. Am. 40, 608 (1950).4 E. F. Daly, Nature 166, 1072 (1950); D. A. H. Brown and V. Roberts,

J. Sci. Instr. 30, 5 (1953); R. C. Beitz, J. Opt. Soc. Am. 43, 773 (1953);P. Gloersen, J. Opt. Soc. Am. 48, 712 (1958).

5 T. B. Thomas and E. E. Schneider, J. Opt. Soc. Am. 41, 1002 (1951).

From the Executive Office

Applied Optics

The Optical Society of America inaugurates the publication of anew bimonthly journal entitled Applied Optics. Its Editor isJohn N. Howard and the Managing Editor, Miss P. R. Wakeling.While members have been hearing much about this new journaland, hopefully, sending in their subscriptions, the best advertise-ment for it is the actual appearance of the first issue. This issuefeatures optical pumping. The Editor wishes to emphasize thefact, however, that while each issue will feature some individualtopic of high current interest, the journal will always welcomecontributed papers on any facet of applied optics. This columnwishes to extend congratulations to the Editors who have as-sembled this issue, thanks to the contributors, and best wishes fora most successful future to the journal.

IES Gold Medal to Deane B. Judd

The members of the Society will no doubt be interested in thefollowing press release made in September, 1961. "The GoldMedal Award for 1961 of the Illuminating Engineering Society(IES) has been given to Dr. Deane B. Judd, the outstandingauthority in the field of color in the United States and probablyin the world." The Illuminating Engineering Society, with morethan 10 000 members, is the recognized authority on lightingstandards. Its Gold Medal is awarded "for the purpose of giving

recognition to meritorious achievement which has conspicuouslyfurthered the profession, art, or knowledge of illuminatingengineering."

Dr. Judd has received other awards such as the Godlove Awardof the Inter-Society Color Council (1957), the Exceptional ServiceAward of the U. S. Department of Commerce (1950), and theJournal Award of the Society of Motion Picture Engineers (1936).The members of the Optical Society of America, of course, areaware that, in addition to being Editor of the Journal of theOptical Society of America, Dr. Judd is a former President of ourOptical Society (1953-1955), as well as a recipient of our FredericIves Medal in 1958).

Dr. Judd is far too modest to emphasize these achievementshimself in this journal, so may this column make this announce-ment to the membership and, in turn, extend to Dr. Judd themost sincere congratulations of all of the members of the Societyfor this well-earned honor.

Membership DirectoryEach member of the Optical Society should be receiving his or

her copy of the new 1961 membership directory early in January,1962. This announcement is being made to the members becausethis is a Fall, 1961 directory. It will be a supplement to the 1961issues of the Journal of the Optical Society of America, and thepages in it will be numbered consecutively following the December,1961 issue. Members may wish to bind this directory with the 1961issues of the Journal of the Optical Society of America even thoughthis supplement will not be received until a month or so after theDecember, 1961 journal.

By the way, are the members of the Society aware that, contraryto the practice of some other journals, the Journal of the OpticalSociety of America is received by its members by the beginning ofthe month of issue rather than by the end of that month, as isdone with some other journals. This is a feat of good managementby the Editor and the Publisher of the Journal.

Vice President for Meetings and Secretaryfor Local Sections

Those members who read the bylaw changes published in theDecember, 1961 issue of the Journal of the Optical Society ofAmerica know that Walter S. Baird, Vice President for Meetings,and Howard Cary, Secretary for Local Sections for some years,retired in December, 1961, and that the work of each of these twoofficers is now being carried on by the Executive Secretary in theExecutive Office of the Society. Actually, the Secretary is verysorry to see this change in officers, because each of these gentlemenperformed his tasks for the Society at considerable expenditureof his own time and effort and made real contributions to theSociety.

The valuable advice and suggestions for Executive Officeoperations from Walter Baird will be missed, since he was chair-man of the Board committee which recommended setting up anExecutive Office for the Society. In the case of Howard Cary, hehas promoted cooperation among the Local Sections by arrangingannual meetings of their officers and an excellent program oftraveling lecturers. He has done this so smoothly and successfullythat he has set a high standard of performance for his successor.

The Society owes both of these gentlemen a very firm vote ofthanks for their services. The Executive Secretary hopes thattheir advice will continue to be available and if this is so, she willtry not to abuse this privilege.

New Officers for 1962

The following new officers were successful in recent elections:President-Elect, Stanley S. Ballard; Directors-at-Large, R. ClarkJones, E. D. McAlister, and G. N. Hass, each for three-year terms;E. K. Plyler for a two-year term; and J. A. Sanderson for a one-

102 Vol. 52

TECHNICAL NOTES

year term. In January, 1962, they will join David L. MacAdamas President and Wallace R. Brode as Junior Past President, plusthe remaining officers listed in the Journal as the official officers ofthe Optical Society of America for 1962.

In closing, all of the members of the Society are grateful to theretiring Past President, James G. Baker, especially for his devotedleadership during his year as President, and to Dr. S. Q. Duntleyand Dr. Victor Twersky for their services as Directors-at-Large.

MARY E. WARGA

Executive Secretary

Errata

1961, Volume 51

ISRAEL GOLDIAMOND AND LESLIE F. MALPASS, Locus of Hypnotic-ally Induced Changes in Color Vision Responses.

In footnote 9, p. 1120, the address of Scientific Publishing Com-pany, 2328 Eutaw Place, Baltimore 17, Maryland, is incorrectlygiven as Princeton, New Jersey.

Book Reviews

The Fermi SurfaceProceedings of an International Conference Held at Coopers-town, New York, August 22-24, 1960. Edited by W. A.Harrison and M. B. Webb. John Wiley & Sons, Inc., 1961.Price $10.00.

One of the greatest scientific problems in this period of extremelyrapid development is the dissemination of information. Theliterature is enormous, and almost no one can follow what is done,even in his own field, without great expenditure of time. Meetingshave grown so large and crowded that it is hard to get much fromthem. A device is growing up to circumvent these troubles: smallconferences on detailed topics, often followed by publishedproceedings. The conferences are stimulating to those attendingthem; the proceedings, invaluable both to those who were presentand those who were not. The reviewer was not present at theconference reported here, though he did attend a similar con-ference a year later for which proceedings will not be published.He finds this volume of the greatest value in following a veryrapidly developing field, as well as in making the later discussionsintelligible. No one working in the field can afford to neglect thismost useful report of progress.

Only three or four years ago, the theories of the Fermi surfacewere very far from detailed experimental verification. In semi-conductors, the methods of cyclotron resonance, magneticinterband transitions, and various other very ingenious experi-ments had shown that energy bands were in principle observable,but a variety of experimental difficulties stood in the way of usingthe same methods for metals. In the years since then, a number ofstriking experimental successes have provided several verypowerful experimental tools for studying Fermi surfaces in metals.We may enumerate the anomalous skin effect, developed byPippard in Cambridge, England; the de Haas-van Alphen effect,known for a number of years for bismuth, but extended to manyother metals by Shoenberg, also of Cambridge; magnetoresistance,known for years, but adapted brilliantly by Lifshitz andPeschanskii, Alekseevskii and Gaidukov, and others in Russia togive most valuable information; cyclotron resonance, now made

practicable for metals by the suggestions of Azbel' and Kaner inRussia, applied by Kip in California and others; oscillatoryultrasonic attenuation, used by Morse at Brown University; aswell as a number of other methods. In some cases, notably copper,a number of these methods have been used, with close agreementin all details; and the theory of energy bands is, at the same time,converging to answers in very close agreement with experiment.It is a field in very rapid, even explosive, development of a mostbrilliant sort, and this volume gives the type of fresh, informal,and yet authoritative account of this development which only averbatim report of a conference can give. It is not only inspiringreading; it is sure to contribute greatly to the development ofthe field.

The difficult task of assembling the book, putting it intoreadable form, and getting it rapidly into print, has been ac-complished very successfully by the editors. It is a field in whichhandsome pictures of Fermi surfaces are coming to be a common-place; these add to the attractiveness of the volume. The publisherhas wisely used a photo-offset reproduction of typed material as amethod of printing, adding to the speed of publication. Thefinancial support of the conference was provided by the Air ForceOffice of Scientific Research and the General Electric Company;they have performed a public service in arranging it and in seeingthat the proceedings were published in the present volume.

It may be useful to close with a few remarks on why thesethings should be interesting to readers of the Journal of the OpticalSociety of America. The optical properties of solids have for sixtyyears been described by the methods of Drude and Lorentz,based on the ideas of oscillating electrons and of the free e ectronsconcerned with conductivity. The theoretical physicistIs haverealized for the last thirty years that this would eventu ally besupplanted, or supplemented, by theories based on our knowledgeof the energy'bands of solids. Until now, there has not been muchone can do with this fact. But the time is now ripe for an extensionof the type of theory described in this volume to the field of opticalproperties of solids. The problem is touched on in this book, butit is destined to become much more important within the nextcouple of years. Anyone interested in the optics of solids, and notfamiliar with modern theories of energy bands and the Fermisurface, would do well to start learning about them.

J. C. SLATERMassachusetts Institute of Technology

Technical Notes

Vibrational Spectroscopy in Optics andSpectroscopy*

D. E. FREEMANChemistry Department, Tufts University, Medford 55, Massachusetts

Since 1959, when the Optical Society of America commencedcover-to-cover translation of the Russian journal, Optika i Spektro-skopiya, the translated version, Optics and Spectroscopy, has con-tained about 150 articles in the field of vibrational spectroscopy.The quality of the translations is high and their content merits theclose attention of spectroscopists. The present review, dealing withthe period from January, 1959, until March, 1961, is not intendedto be exhaustively comprehensive but is focused on selected topics,so that some articles, especially those of a more empirical nature,are omitted.

A. Redundant Coordinates. One of the principal aims of normalcoordinate treatments is to analyze frequency data so that theeffect due to equilibrium geometry and masses is separated fromthat due to the electronic potential in which the nuclei vibrate.Unfortunately, the purely vibrational problem does not generallyyield a unique set of force constants and some relief from this

January 1962 103

TECHNICAL NOTES

difficulty is frequently sought by regarding certain force constantsas invariant for molecules which are similar but not necessarilyisotopic. Both the concept of transferable force constants and thepractice of interpreting, in terms of the more subtle manifestationsof valence forces, the slight variations in the values of suchconstants for the same atomic group in slightly differing electronicenvironments, are based on two related hopes: first, that a forcefield can be formulated as a totality of contributions from in-dividual members (springs), with pair-wise interactions betweenthem; and second, that each constant is physically meaningfulin its own right. These considerations are well known but requireadditional comment in the case of structures which are geo-metrically redundant.

If, in a complex molecule such as cyclohexane, each bond andangle is regarded as a component which is already understoodfrom studies of force constants of simpler systems, then it isnatural to try to assemble the force field from these alreadyknown constants, even at the expense of introducing redundantcoordinates. In other cases, such as benzene, symmetry argumentsindicate that a C - C stretching constant and a C - C - C bendingconstant be associated with six C-C bonds and six C-C-Cangles, respectively, even though the complete definition of allpossible planar skeletal displacements requires only nine (andnot twelve) independent coordinates. Similarly, whenever acomplete quadratic force field is assembled for a set of redundantcoordinates, it will contain a greater number of force constantsthan required in the most general sufficient quadratic potential.This necessary and sufficient number is, of course, 4 1i ni (ni+ 1),n• being the number of genuine vibrations in the ith symmetryspecies. For any particular molecule it is true that an over-sufficient set of force constants can be replaced by a sufficient setwithout affecting the observable spectroscopic quantities for thatmolecule, and the reviewer does not seriously advocate that morethan the sufficient number be used, such a procedure beingimpracticable anyway for most large molecules. Instead, what isdesired is to be able to select freely a number of force constantsnot exceeding this sufficient number from among the over-sufficient number associated with a set of redundant coordinates.

The difficultyl-3 in justifying this approach resides in the factthat derivation of the secular equation leads originally to thematrix equation.

[F--G-IXN]I=O,

while the prescriptions of Decius4 or El'iashevich5 lead to thematrix G of kinematic coefficients and not to G-1. Premultipli-cation of the above equation by G gives

[GF-- GG- 1X1l = O,and this yields

[GF-IXIV=Oonly if G and G-1 are nonsingular. But if redundant coordinatesare present, neither G nor G- 1 has an inverse and the step leadingto the last equation cannot be taken. Gold el al. give an argumentto circumvent this difficulty, but conclude that the F matrix,referring to a redundant set, is singular. Godnev et al*,2 show,however, that the use of a singular F matrix does not seem to beobligatory.

If their considerations2 be accepted, the procedure for practicalcalculations is as follows. Select a set of n coordinates of whichone, say, is redundant (the argument is readily extended to morethan one redundancy); apply a coordinate transformation inn-dimensional space to the redundant set, which may be regardedas a column vector of n components of which only (n-1) areindependent, so that a transformed vector is obtained in whichthe redundancy appears explicitly as zero. Thus, if the redundancyis 1i-1" ciri=O, then

s., 1 1 O*...O

S2 0 1 ...OS[-100 0. .Is0ij[ o..1

0 Ci C2" "Cn-1

0 I r2J r.-i

c~a- -, Yn

or more briefly, S=3Ar, Al being square and nonsingular. Thesecular equation, IGF-IAI =0, in which the matrices F and Gare referred to the redundant coordinate set r becomes, on multipli-cation on the left by I-IfI and on the right by M-1-l,

JMGFM-1-IXj =0IMGMAB'f_-FMV- 1-IX I=0

J G'F'- IX =0,

where G'=-MGM1[ and F'=Mf -FMl- . But, because the rows andcolumns of G' satisfy the same linear dependences as do thecoordinates, G' will contain a row and column of zero elements.Hence,

[ G I'F<i I I -[L 0]1[ 0 1 1 ] I--0,where H is a certain column vector with (n-i1) components andthe subscripts, -- 1, designate matrices of order one less than thosepreviously unsubscripted. The above equation is equivalent' to theequations, X=O, and IGU'F_<'-I_ X(=0. Notice that G1

1',F_1' are obtained from G', F', respectively, simply by omittingthe row and column corresponding to the zero redundant co-ordinate and that F' is the matrix resulting from the eliminationof rY from the potential energy. Such, then, is the procedure forreducing the degree of the secular equation; alternatively, if theredundancy is retained, a zero root will be obtained in additionto the nonzero roots which are identical to the roots of the reducedsecular equation.

In cases where the molecular symmetry is utilized, the re-dundancy belongs to a particular symmetry species, and, byjudicious choice of the transformation from internal to symmetrycoordinates, the redundant symmetry coordinate can be taken asidentically zero and the matrix M in S=Mr can be chosen to beorthogonal; then M=M-J and

F' =MFrJ, G'=MGA7.

By using these so-called symmetrized matrices, F' and G', thesecular equation of degree n, with redundancy included, becomes

IG'F'-mJI =0.

The corresponding secular equation of reduced degree, (n-i1)

I G-I'F- '- I-1X I = 0,all the roots of which are nonzero and identical to the nonzeroroots of the preceding equation. The reduced symmetrizedmatrices G_1 ' and F_1 ' are formed simply by omitting the ap-propriate row and column from the symmetrized matrices G' andF'. However, for this last statement to be valid, M should bechosen as an orthogonal nXn matrix and not merely an orthogonal(n-1) X (n- 1) matrix.

B. Normal Coordinate Analyses. The results of normal co-ordinate treatments are summarized in Table I and additionalcomments are presented as a series of notes following the table.In interpreting the table, it should be noted that entries under"Average Deviation" will depend on precisely which of the severalusually possible assignments of experimental frequencies ischosen. The force fields employed are all of the valence type withinteractions, no use having been made of the Urey-Bradley typeof field. Certain terminological differences exist between Russianand Western usage and these are given immediately below.

Russian Usage Western UsageA: matrix of kinematic coefficients G: matrix of kinetic energy elementsU: matrix of dynamic coefficients F: matrix of force or potential

constantsq, y: natural coordinates of changes r: internal coordinates.

of bond length and bond angledynamic coefficients in units of cm-

2 force constants in units of dynescm-'; if a force constant isexpressed as F dynes cm-1 oras F' cm-

2, then F =4ir2c2mHF'

=0.05937 IF'method of El'iashevich and Stepenov Wilson GF matrix method

104 Vol. 52

TECHNICAL NOTES

In addition to the theoretical studies listed in Table T,7-5" thereare others dealing with the theory of vibration of silicates 7ab andpolymers,8 the derivation' and application'0"' of isotope rules, thecalculation of frequency and form derivatives for molecules withsymmetry," the effect of free rotation on normal frequencies,"3 theanharmonic vibrational constants of water."4

C. Calculation of Intensities. The interpretation of infraredintensities for polyatomic molecules is attended by practicaldifficulties of obtaining measurements which represent trueintensities and by theoretical difficulties of ambiguity of the signof dipole derivatives and non-uniqueness of potential constants.' 2

In the zeroth approximation of the bond moment or valence-optical scheme,' the main assumptions are that the nth bonddipole, Lj-'<, is directed along the nth bond length; that themagnitude, M(n), depends only on changes, r,,, in the nth bondlength; and that direction cosines, cos (ni), depend only on changes,0,, in interbond valence angles. The number of electro-opticalparameters (bond moments, etc.) occurring in this zeroth approxi-mation is acceptably small but the difficulty is encountered thatnonidentical values of a parameter are sometimes obtained fromvibrations of different symmetry species.

In the hope of avoiding this trouble, Sverdlov has proceeded tothe first approximation of the bond-moment scheme, in which theabove-mentioned assumptions are relaxed, so that

0gA W (/A W cos (ni)#0, 0 r-,--- - O,

Ort a00. Ort

i.e., parameters representing interactions are introduced, but itis still assumed that bond dipoles are directed along bond lengths.This scheme has been tested on various types of molecules(methyl halides;" CH 4, C2H6, C2D)54; SO2, NH3, PH355; CF 4,C2F 6

66 ; BF3, NF3, SiF 4, SF 86 7 ; deuteroethylenes"; isotopic

methanes'9 ; benzene"0 and it is possible to obtain bond momentconsistently from different symmetry species, the former in-consistency of the zeroth approximation being now absorbed intothe electro-optical parameters representing interactions. Thedisadvantage of the method is that the number of such interactionparameters often exceeds the number of observed intensities sothat not all of the parameters can be evaluated separately. Thissituation is quite analogous to that met on proceeding from asimple valence force field to a general quadratic force field. Indeed,the nonuniqueness of a quadratic force field analogously aggra-vates the former situation, For example, the frequencies 522, 219cm-1 of C2F 8 are interpreted differently by Sverdlov56 and byCrawford,8 1 not as to their symmetry species (which is agreedto be e,) but as to their respective normal modes within thisspecies; both authors reproduce the frequencies by using forceconstants which are transferable between CF 4 and C2F6 butCrawford employs a Urey-Bradley potential whilst Sverdlovprefers a valence potential. Hence, each author favors a differenttransformation from normal to symmetry coordinates, and, in thefirst approximation of the bond moment scheme, Sverdlov claimsto be unable to produce (from Crawford's transformation)electro-optical parameters which are consistent with certaincriteria with which his own (i.e., Sverdlov's) results are consistent.

Recently, Sverdlov2 has investigated a so-called "generalizedvalence-optical scheme" in which it is no longer assumed thatthe bond dipole is directed along the bond length, i.e., transversemoments are introduced. In its first approximation, this schemerequires a very large number of electro-optical parameters, but,in its zeroth approximation, the number is much more limited.Thus, in its zeroth approximation, four such parameters sufficefor a treatment of the SO2 molecule, whereas in the first approxi-mation without transverse moments,5 seven are formally required,while in the zeroth approximation without transverse moments,"inconsistent values are obtained from different symmetry species.The method looks more promising than the previous one" but itremains to be seen how well these transverse moments can repre-pent what seem to be lone-pair effects, e.g., in NF,.

Gribov6," 4 has presented the zeroth and first approximations ofthe valence-optical scheme in a formalism which has some ad-vantages for automatic computation. The equivalence of Gribov'sformulation to an earlier and apparently dissimilar formulationof Ferigle and Weber 65 is demonstrated by Kovner and Snegirev.66Gribov8 7 and Sverdlov'8,'9 also discuss some conditions for theappearance of characteristic intensities and polarizations, andfind that the conditions for the former are the more stringent.

The calculation of Raman intensities within the valence-opticalscheme is extended from benzene to toluene. 70 ,71 Owing to in-completeness in the experimental data for toluene, the procedureof Yoshino and BernsteinT1 is modified and the approximationis made that the electro-optical parameters of benzene andparaffinic methyl are transferable to toluene. From such param-eters and the vibrational forms, 78 values are predicted which matchmoderately well the observed values of Raman intensities anddepolarizations. A metallic model 74,76 has also been used topredict, among other things, approximate Raman intensities ofsome totally symmetric vibrations of benzene and toluene.

The important paper76 in which are derived expressions forRaman intensity, which differ from the usual Placzek expressions,is scheduled for separate comment by others.

D. Temperature Dependence of Intensities. According toPlaczek, 77 the dependence on frequency and temperature of theStokes and anti-Stokes Raman lines of a diatomic harmonicoscillator is given by

1s=K(vo-v)4 (1-e-)- 1, IAS=K(vov) 4(e"--l)-1, u=hv/kT,

where K is constant. Thus, neither Is nor IAS is temperatureindependent, nor is their sum or ratio; and, from these formulas,the temperature coefficients of Stokes intensity, of anti-Stokesintensity, and of the ratio of anti-Stokes to Stokes intensity areall positive.

For a diatomic harmonic oscillator, the net absorption ofinfrared radiation of frequency v is determined by the algebraicsum of absorptive transitions (from states v to v+ 1) and emissivetransitions (from states v+1 to v), summed over v. Thus,

L= L-I, K''(1-e-u)-1- (eu'- 1)-']= K',

where K', and hence I,, are temperature independent. Such aconclusion has been reached repeatedly4,7T,79 for the polyatomicharmonic oscillator. However, there are several papers80 -8 4 whereinfactors of the form, (1 -e-t)-, are used to describe the temperaturedependence. The enthymematic fallacy could arise in at leasttwo ways: (a) from an oversimplified analogy of infrared absorp-tion intensity to Stokes Raman intensity, which in Placzek'stheory, exhibits such a factor. However, in the Raman effect, theanalogs of the two terms, 1, and 1,, are the Stokes and anti-Stokes intensities, respectively; these latter, occurring at differentfrequencies, are separately observable while the former arecoincident in the infrared spectrum; or (b) from assuming that I,contributes negligibly to the directed infrared beam travelingthrough the absorbing sample; this idea, expressed in the initialpaper of Crawford and Dinsmore"' has long since been corrected.86

Recently, Lisitsa and Strizhevskii 83 have predicted that theabsorption intensities of noninteracting molecules withoutmechanical or electrical anharmonicity are temperature in-dependent and they show how temperature dependence may arisefrom anharmonicity. However, no explicit account is taken ofnormal mode degeneracy and even in the harmonic approximationit is presently considered that only nondegenerate vibrations willhave intensities which are temperature independent87 and thatthe Raman intensities of degenerate vibrations will exhibit atemperature dependence different from that of nondegeneratevibrations.88

The following are the units used for infrared intensities (cf.references), "2," The measured integrated intensity is

k." = b-l f In (1o/I),,d,, cmn-2,

105January 1962

TECHNICAL NOTES

TABLE I.

Molecule

XHa, XD3(X =N,P,As,Sb)

POCl3, POBr3,PSCIa, PSBr,

PO(OCHs)a, PS(OCHa)s

ZrXs, (X =F,C1,Br,J)PbX4, (X =F,Cl, Br, I)YX4

Si(CHa)4, Si(CDs)4CHaSiHa(CHI) 2SiH2(CH3) aSiH

CH2=CHC1, CH2=CDCICH2 =CClhCHa =CBr2, CDs =CBr2,CHD =CBrsCH2 =CHF and sevendeuterated species

methylallene1,1-dideuteroallene

1,3-butadiene

Isobutane: HC(CHa)a,DC (CHU a

2,3-dimethylbutane

methylcyclopropane1, 1-dimethylcyclopropane

o-xylene

toluene

biphenyl anddeuterated derivatives

cyclopentane: CaHasCoDio

C.5Dto

inethylcyclopentane

cyclopentene

naphthalene

No. offorce

Symmetry Reference const.

Ca, a, b 6

C',

Cau, C3, C, d

TdTaTd

TdCa,C2VCa,

C,C2VCsV

eg

bh

c 12 each

26

555

1540

samesame

292323

AverageNo. of devia-freq. tiontalc. (cm-o) Zi i½n

6 0

6 each

4 each4 each4 each

19 each122522

12 each12

12 each

32 12 each

C, kC2s k

C2h, C2V

C3,

C2h, C2a, C2 n

C8 0Cs, 0

Csv p, qCs, r

D2h S

Dss

Dsh

C,Cs,

t 12

u 25

v, w 27

x

y

13

44

D2h z

Vibra-tional

(n +-1) forms Reference

6 no aa

5 12 yes bb

yes cc

154

14

5654

I15

12

10

55

5537

109124

512929

nonono

yesyesyesyes

nonono

dddddd

eeffffff

gggggg

no gg

23 16 165 no hh15 8 42 no hh

24 16 97 no ii

22 17 124 yes ii

54

3039

46

35

no kk

14 244 no 11214 no 11

9 337 yes mm9 233 yes mm

56 14 279 no on

171717172323

46

787115291116

52 yes

no

no

00

00

00

yes oo33 14 160 no oo

189 no PD

" See reference 16.b See reference 17.c L. S. Mayants, E. M. Popov, and M. I. Kabachnik, Optics and Spectros-

copy 6, 384 (1959).d L. S. Mayants, E. M. Popov, and M. I. Kabachnik, Optics and Spectros-

copy 7, 108 (1959).eI. N. Godnev, A. M. Aleksandrovskaya, and I. V. Riginia, Optics and

Spectroscopy 7, 172 (1959).' A. M. Aleksandrovskaya, I. V. Rigina, and I. N. Godnev, Optics and

Spectroscopy 7, 495 (1959)."9I. N. Godnev and A. M. Aleksandrovskaya, Optics and Spectroscopy10, 14 (1961).

h I. F. Kovalev, Optics and Spectroscopy 6, 387 (1959).See reference 24.

1 L. M. Sverdlov, Yu. V. Klochkovskii, V. S. Kukina, and T. DMezhueva, Optics and Spectroscopy 9, 383 (1960).

k L. M. Sverdlov and M. G. Borisov, Optics and Spectroscopy 9, 227(1960).

I L. M. Sverdlov and N. V. Tarasova, Optics and Spectroscopy 9, 159(1960).

T. I. Kuznetsova and M. M. Sushchinskii, Optics and Spectroscopy10, 20 (1961).

n R. I. Podlovchenko, L. M. Sverdlov, and M. M. Sushchinskii, Opticsand Spectroscopy 6, 96 (1959)."0 L. M. Sverdlov and E. P. Krainov, Optics and Spectroscopy 7, 296(1959).

P M. A. Kovner and A. M. Bogomolov, Optics and Spectroscopy 7, 444(1959).

q A. M. Bogoanolov, Optics and Spectroscopy 10, 162 (1961).r A. M. Bogomolov, Optics and Spectroscopy 9, 162 (1960).

G. V. Peregudov, Optics and Spectroscopy 9, 155 (1960).See reference 37.

" See reference 38."v See reference 39."See reference 40.See reference 41.

Y See reference 42.SSee reference 10."" Zero-order (harmonic) frequencies are used. Comparison with an

essentially similar calculational shows that many of the interaction con-stants have seemingly different values in the two studies; but the errors

associated with these constants (based on assumed errors of 5 cm-1 in thezero-order frequencies and 0.5' in the valence angles) have huge calculatedvalues"6 and the discrepancies are therefore fictitious-a good example ofavoiding the fallacy of over-estimating the significance of the numericalvalues of such constants. Of the diagonal constants, the As-H stretchingconstants most exceed the estimated errors, and differ by about 5%.Application of the approximate method of partial frequencies17 yields quitegood results for these molecules with widely separated frequencies in anyone symmetry species.

bb As admitted by the authors, not much weight should be attached to thenumerical values of twelve force constants chosen to be consistent withonly six frequencies. Tetrahedral geometry is assumed. A recent paper,'

8

in which the Russian work is ignored, deals with phosphoryl and thio-phosphoryl chlorides and fluorides. Only by regarding angles such as(100±-2)" as insignificantly deviant from 109' 28', can the geometry citedbe reconciled with the symmetry coordinates given. Also, the F matricesfor species as and e are adjusted separately to reproduce the observedfrequencies for the al and e species, respectively; this unsystematic pro-cedure avoids negating mathematically necessary relations (arising fromsymmetry) between these matrices only by using, in the valence force field,a number of parameters, viz., 16, which is not less than the number of Felements, viz., 12, (and, a fortiori, not less than the number of observedfrequencies, viz. 6).

coVarious rotational isomers are treated. Characteristic stretchingfrequencies for P--O bonds (1215-1309 cm-') and P-S bonds (607-748cmu1) are listed for about 50 organophosphorous compounds.

dd The method of progressive rigidity'9

is applied; equilibrium geometry,if unknown, is estimated semiempirically. See also reference 20. Recentlymeasured experimental frequencies for zirconium halides2i agree well withthe predicted values."ee Five out of nineteen frequencies are forbidden in the infrared andRaman spectra. Force constants initially transferred from CH3SiH, aresubsequently adjusted. Influence constants (i.e., elements of the inversematrix of force constants) are calculated. No observed frequencies areavailable for Si(CDa)4.

ff More accurate equilibrium geometries are now available from-amicrowave study," in which, also, torsional modes of trimethylsilane areconsidered. One frequency of methyisilane and four of trimethylsilane areforbidden in the infrared and Ramanrspectra. Recent-experimental'fre-quency data'- not utilizing Kovalev's calculationsU are available for di- andtri-methylsilanes. The torsional frequencies for dimethylsilane are not

106 Vol. 52

I

mn

TECHNICAL NOTES

observed, nor are they calculated; otherwise, Kovalev's calculated fre-quencies agree quite well with the new experimental assignments exceptin three cases (excluding the Raman frequency 2096 cm-', a misprint23which should be read as 2906 cm- ). The experimental frequencies 643cm-' (dimethylsilane) and 616 cm-1 (trimethylsilane) are observed only inthe infrared, even though they are symmetry-allowed in the Ramanspectrum; and these are the two frequencies most definitely at variancewith the computed frequencies. Their acceptance is said to imply strongcoupling of Si-H bending with methyl rocking motions and the absenceof characteristic Si-iH bending modes in both molecules. For dimethyl-silane, the calculated normal modes predict this sort of coupling for thecalculated frequency 841 cm-5; this is also the region which has previouslybeen associated2" with Si -H bending in trisubstituted silanes. Hence, theassignments of 643 cm-1 and 616 cm-1 are not unexceptional and wouldbe contra-indicated by the normal coordinate analysis, were it not thatthe reliability of that calculation seems doubtful in this frequency region,where, corresponding to the fairly secure experimental assignment of 591cm-' to the a2 species for dimethylsilane, the calculated prediction is 760cm-1. A similar normal coordinate calculation for (CHa)2SiD2 and(CH3)aSiD should be helpful.

a9 With only 19 Urey-Bradley force constants26 and the same assignmentof observed frequencies, the average deviation between calculated andobserved frequencies for vinyl chloride and vinyl chloride-di is 18 cm-1.

hh The force constants are transferred from propene and allene. Observedfrequencies for comparison with those calculated are lacking for mono-deutero-, 1,3-dideutero-, and trideutero-allenes. See also reference 7.

ii The trans-model yields calculated frequencies which can be correlatedwith the observed spectrum more convincingly than those of the cis-model.The force constants are transferred from propene and then adjusted.

ji The CsU symmetry and equilibrium geometry are now better estab-lished.'8

Four vibrations are forbidden in the infrared and Raman spectraand one other is not observed. Force constants are transferred from ethaneand propane.

kk Of the four rotational isomers investigated theoretically, the calcu-lations indicate the existence of two in the liquid phase. Force constantsare transferred from ethane and propane.

11 Force constants are transferred from alkanes and cyclopropane. Seealso reference 29."' Two twisting vibrations of xylene and one of toluene are ignored.Force constants are transferred, with some modifications, from benzene.From the calculations, vibrations of substituted benzenes are classifiedas characteristic in (a) frequency and form, (b) frequency only, (c) neither(a) nor (b). Vibrations of monosubstituted benzenes have recently beentreated independently.30 The vibrational forms given in the two studiesare essentially similar, even for the 1211 cm-' vibration (a, species) wherethe similarity is perhaps least marked. See also reference 31. For xylene, inthe bt species, the calculation by Bogomolov"2 favors an assignment corre-sponding to the Mair-Hornig assignment for benzene"3 and also shows thatthe b5 vibrations 1439, 1460 cm-' represent CH deformations in which CHbonds belonging to both the ring and the methyl group coparticipate,while not much such coupling exists in the CH deformations in othersymmetry species."n" Force constants are transferred from benzene. The latest interpre-

tationa4

of the vibrational spectrum of biphenyl from absorption measure-ments on single crystals using polarized infrared radiation is in terms of thepseudo-C2u model. This investigation supersedes previous work"5 andcontains a discussion of differences from Peregudov's assignments. Also, thevibrational structure of the phosphorescence spectrum

86 of biphenyl at

90'K yields five frequencies; of these, all except 315 cm-1 are assigned astotally synmmetric,4 a fact, which, in the absence of phosphorescencepolarization data, is merely suggestive that the Raman frequency corre-sponding to 315 cm-' may be totally symmetric.""°Although both Lebedev""38 and Sverdlov"9 agree that the spectraof cyclopentane and its fully deuterated derivative are assignable on theassumption of Dsh symmetry, the latter author's treatment seems prefer-able. The two most noticeable differences in their assignments are for thesymmetry species a," and e,". As well as agreeing to the shortcomings ofLebedev's work listed by Sverdlov, the reviewer would add that theassumption of cyclic skeletal planarity leads to three, not two, dependencesamong Lebedev's internal coordinates. These are

y'51+'f'5+'l'34+7J45+7"5 =0Qa+0.309 (Os +04) -0.809(0,+05)

- 1.185 [E-15 +0.258 (-±2 +',45) -0.986 (Y23 +Y34)] =0

1.244(02 -Q4) +0.786(Q0 -08) +1. 6 18('r"2 -y45) +(Y2" -Y34) =0,

of which only the first is given correctly by Lebedev. Also, in Sverdlov'sseventh and eighth equations, the quantities a should be reciprocals of C -Cbond lengths (and not ratios of CH to CC bond lengths); and, in the seventhequation, (iab -'Ya,) should be replaced by (,'bs+yo,). Sverdlov does notquote adjusted values of valence force constants but computes a set ofinfluence constants

40 and concludes that the C -C bond is weaker in

cyclopentane than in ethane, that neighboring C -C bonds interact ratherstrongly and that the CCC angle is much stiffer than in acyclic compounds.

Lebedev4" also calculates the frequencies of methylcyclopentane assumingC, symmetry; but the increased number of frequencies now belonging toonly two symmetry species and the crowded experimental spectra (bothinfrared and Raman) render identifications of calculated and observedfrequencies less convincing than for cyclopentane. Cyclopentane is treatedas a planar C2, model42; most of the force constants are transferred fromacyclic olefines but some (eight out of forty-four) are adjusted.

PP Zhirnov43 reinterprets the vibrational spectrum of naphthalene byapplying isotopic sum and product rules to CtoHs and CnDs. For somesymmetry species containing CH stretching frequencies, his assignmentsimply product-rule ratios (of CioHs to ClsDs frequencies) in slight excessof the theoretical (harmonic) ratios; however, the reverse would be ex-pected, since the effectiveness of anharmonicity in causing differences fromharmonic frequency values is largely concentrated in the CH and CDmotions, and more especially in the former. Moreover, in applying isotopicrules, one misassignment readily begets another, and, since several mis-assignments result directly from ignoring the work of Bolotnikova4",4'and Craig et al.,4" it is not surprising that Zhirnov's results deviate seriouslyfrom those most recently published."s-'0 Zhirnov also reports an approxi-mate calculation,"' the purport of which is to explain why two frequencies(992, 3070 cm-1) appear in the spectra of both coronene and benzene.

where b cm is the path length and co cm-' is the frequency. Theintegrated intensity coefficients, k.,, are defined below for gases,liquids and solutions.

For gases, k,==k.'X (cRT/p) cm' sec' mole-',for liquids, k. = ka'X (cM/p,) cm1 sec-' mole-',for solutions, k.=k.'X (cM1/CvpT) cm' sec-t mole- ,

where c cm sec-1 is the velocity of light, M g mole-' is the molecularweight, pT g cm- is the density at temperature T, and CG is adimensionless measure of concentration.

For gases, Smirnov and Bazhulin7' use a technique of measure-ment which is admitted to be less accurate for absolute infraredintensities than the Wilson-Wells method and their absoluteintensities agree with those published elsewhere only to withinabout 20%; doubtless their relative intensities (at differenttemperatures) are more accurate, but, to what extent, it isdifficult to judge. Some of their quoted changes of k. with tem-perature, e.g. for CS2, are very large and an explanation is soughtin terms of intermolecular interactions, the intramolecular effect(anharmonicity) being assumed small. It is puzzling that, forCHCIa, the relative intensity of the CH stretching vibration (forwhich a frequency of 2970 cm-1 is quoted, as compared to theaccepted value"° of 3034 cm-1) increases by 40% between 25'Cand 275°C while, for CHBr3, the relative intensity of the CHstretching vibrations' 4 increases by only about 5% between 150"and 300'C; similarly, the (v,+s4) combination seems less tem-perature-dependent for CHBr3 than for CHCl3 . In studies"", ofthe temperature dependence of infrared intensities of bands ofgaseous CC14, the occurrence of Fermi resonance is a complicatingfeature (cf. reference 91), but it is concluded7 ' that electricalanharmonicity plays an important part in it. It is strange, in viewof the generally significant effect of twofold isothermal pressureincreases on absolute intensities,"2 that no such effect for tenfold

pressure increases is observed for the combination bands of CCI,,although the doublet studied displays marked temperaturedependence. For the gases CO2 and N2, the temperature depend-ences" of the Stokes-Raman intensities of the stretching vibrationsdo not disagree with the theoretical predictions, but the intensitychange over the temperature range studied is too small for areally severe test. One of the difficulties in investigating thetemperature dependence of either infrared or Raman intensitiesin gases is the concomitant increase of pressure which occurs onheating. None of the relative intensities in the above studies iscorrected for pressure, and, although the increase in relativeintensity resulting from an increase in temperature is greaterthan the increase resulting from the corresponding, isothermalincrease in pressure, it would seem preferable to study the tem-perature effect under isobaric conditions. Such desirably criticalexperiments9",94 for the Raman intensities of some gases revealpositive temperature coefficients for Stokes intensity, anti-Stokesintensity, and for the ratio of anti-Stokes to Stokes intensity, inqualitative agreement with theory. Some experiments relatingto the origin of band width in the Raman spectra of simple gaseshave been reported."

The temperature dependence of Raman intensities in liquidshas received some attention. The two studies"3" already referredto in connection with gas intensities, also contain data on the samesubstances in the liquid phase. The temperature coefficients ofStokes intensities are usually larger in magnitude and alwaysopposite in sign, relative to those for the gas phase; however, thetemperature coefficient of the ratio of anti-Stokes to Stokesintensity is positive, as for a gas; indeed, the ratios observed forliquids are rather close to the theoretical estimates for gases.Undoubtedly, the negative temperature coefficients for the Stokesintensities in the liquid phase result from the important inter-molecular interactions which are absent in the gas phase. Such

107January-1962

TECHNICAL NOTES

negative temperature coefficients are also found for liquid m andp xylenes,'6 though the observed intensities are not corrected fortemperature variations of refractive index and density, whichare said to exert a small net effect.

The temperature dependence of infrared intensities of liquidshas also been studied. Bazhulin and Smirnov,"1 having examineda series of polar and nonpolar liquids and having found negativetemperature coefficients for almost all the bands, suggest inter-molecular interactions as the major factor; their results for liquidCH3I disagree with earlier work97 in which positive temperaturecoefficients of integrated intensities are found for three funda-mentals. Lisitsa and Tsyashchenko, having previously recordedfrequencies and intensities for liquid CHBr3 1" and CHC13 9" (andobtaining, for CHCl,, intensities only about 60% as large as thoseobtained by dispersion methods)"' proceed to examine thetemperature dependence of intensities. For CHBr3,1"' theintensities of the fundamentals P, (symmetric CH stretch), V4(degenerate CH deformation), and v5 (degenerate CBr stretch)decrease linearly with increasing temperature, most steeply forP4, whilst the intensities of 2v,, 2

V4, 2s', (vj+V4) are practically

independent of temperature; for CHCI0,,"a the intensities of P,and Y4 decrease linearly with temperature, more steeply for vi,while the intensities of 2 v,, 2 P4 are practically independent oftemperature, although those of (P5+N4), (v2+V6), (Pa+v6) diminishappreciably with increasing temperature. An empirical correlationis suggested between the coefficient of cubic expansion of suchliquids and their mean temperature coefficients of intensities.In these studies, intensity ordinates in graphs are labeled in unitsof cm-', though it is stated in the texts that density correctionsare applied, so that units such as cm mole-' or cm2 sec-' mole-'would be dimensionally more appropriate. Some experimentaldifficulties in measuring intense absorptions for liquids have beendiscussed.102b

Intensity changes accompanying a phase change have beeninvestigated. On going from liquid to vapor, the integratedintensity of Y, for CHBr3 is decreased (cf. reference 103) by afactor of 6 and that of the combination band (V1+s 4) in bothCHBr3 and CHC13 is also diminished,'4 For these molecules,intensity changes on going from liquid to polycrystalline phase" 4

have been recorded and discussed in terms of Davydov's theory.In order to avoid the problem of Fermi resonance, which occursin CC14, CBr4 is chosen for a study of the effect of phase changeon intensity."' However, due to experimental difficulties, onlycombinations and overtones are considered; for these, decreases ofintegrated intensity are observed on going from liquid to crystal-line phase but increases result from further cooling of the solidphase, whereas, in the liquid phase, these integrated intensitiesare practically independent of temperature.

Smirnov"6n has studied the temperature dependence of infraredintensity for solutions by examining the influence of the dipolemoment of the solvent, it being already known" that a strongertemperature dependence is often observed for polar, as comparedto nonpolar, pure liquids (although no such polarity effect isobserved in Raman spectral"). For solutions, it is found thathighly polar solvents cause a definite but not large increase inthe magnitude of the temperature dependence. No treatment ofthe effect of solvent on Raman spectra has yet appeared whichis as comprehensive as Buckingham's theory for infrared spectra,"0'though Pivovarov"09 has presented some theoretical ideas. Someexperimental difficulties in determining the effect of refractiveindex on the Raman intensities in liquids"5 (cf. reference 111),experimental studies'12 of the temperature dependence of Ramanintensities in solids (cf. reference 113), and of the influence ofrefractive index on the temperature dependence" 4 have also beenreported.

E. Other Problems. (1) Adsorbed molecules. Since the firstinfrared spectroscopic study of a solid-gas system,2 " numerousRussian investigations have been devoted to adsorbed molecules(see references 116, 117). Filiminov"1' studies the perturbation ofsurface hydroxyl groups on silica gel, alumino-silica gel and

microporous glass by various adsorbates and concludes thatelectron-donor systems (ether, amines) are adsorbed on the acidichydroxyl surface groups and that alcohols form a strong hydrogenbond between the alcoholic oxygen and the surface hydroxyl"';spectroscopic evidence"50 is also found for acceptor-donor bondsfor aluminum or stannic halides complexed with nitric oxide,acetonitrile, or other donors and the same characteristics in theinfrared spectra appearn1s when such donors are adsorbed onalumina or, to a lesser extent, on silica.

In two papers,"2"12 of somewhat overlapping content, theinfrared spectra of nitric oxide adsorbed on transition metals(Fe, Ni, Cr supported on alumina gel), on their salts (also similarlysupported), and on their oxides are examined in detail. In no caseis a band ever observed suggesting that nitric oxide acts as anelectron-acceptor. For metal substrates, most of the absorptionintensity is due to a cationic species NO+, and the frequency shift(from 1876 cm-' for unperturbed NO to above 2000 cm-1) issurprisingly large for a species so weakly chemisorbed; other lessintense absorptions at lower frequencies suggest other species,bound more or less covalently to the surface. For transition metaloxide substrates, the spectra indicate that the three types ofadsorption which occur are (a) adsorption at oxide sites (<1700cm-1), (b) adsorption at metal-ion sites (>1700 cm-1) and (c)general van der Waals adsorption of surface dimers, N202. Ofthese, only the first occurs for nontransition metal oxides such asalumina. The spectra observed for adsorption on salts are of twotypes, there being observed (above 1800 cm-') either one or threebands; the former is the case for a cation with an even number ofd electrons and the latter for a cation with an odd number. Thisbehavior is correlated with pictorial representations of the modesof bonding.

In an investigation of the adsorption of water vapor on micro-porous glass as a function of the degree of hydration of its surface,Sidorovu4 concludes that, for a hydrated surface, the active sitesare surface silanol groups linked together by a hydrogen bondand that, for a dehydrated surface, centers of a second kind areinvolved; the previously held view," 5 that free silanol groups arenot responsible for the adsorption of water, is still maintained,so that disagreement with McDonald's results"' for an amorphoussilica surface still exists.

In contrast to the solid-gas systems most frequently studiedspectroscopically, a preliminary examination in the OH overtoneregion, of a solid-liquid system (adsorption of methanol or phenolfrom carbon tetrachloride solution onto porous glass) has beenbegun."27

(2) Hydrogen bonding. Several studies are addressed to thequestion of hydrogen bonding. One study reveals that tertiaryacetylenic amines with a terminal acetylenic group can formintermolecular hydrogen bonds"' (cf. reference 129). Two recentindependent investigationsss1ul dealing with hydrogen bondingsin mercaptans agree experimentally and indicate that hydrogenbonding occurs, but differ in interpretation of the kinds of equi-libria involved.

The original considerations of Lord et al.,"' concerning thedetermination of the equilibrium constant and integrated absorp-tion coefficient for a hydrogen-bonded complex, the absorption ofwhich is superposed on that of the uncomplexed monomer, havebeen reconsidered by Bulanin et alY.'; by correcting an approxi-mation in the earlier work, they obtain recalculated equilibriumconstants which are appreciably smaller and in better agreementwith values deducible from measurements of vapor pressure, e.g.,the equilibrium between deuterochloroform and diethyl ether,involving a 1:1 complex, has a recalculated equilibrium constantequal to 0.33 liter mole-' (instead of 0.8 liter mole-'), as comparedto 0.37 liter mole-' (calculated fr'om vapor-pressure data on theassumption of ideal solutions).

For inorganic compounds, the effects of hydrogen bondingon OH and OD deformation frequencies have been investi-gated"1," and a qualitative discussion is given"1 on the mecha-nism of formation of a strong hydrogen bond; in this series of

108 Vol. 52

TECHNICAL NOTES

papers, the ability of (OSiOH)'-ions and molecules of the type,R3SiOH (R being C2H5, C6H5), to participate in strong hydrogenbonding is ascribed to the presence of vacant 3d orbitals and anincrease in the role of p~r-d~r bonding between 0 and Si atoms;the hydrogen bond in acid germanates"7 is explained in similarterms.

No experimental study of hydrogen bonding by Raman spectros-copy seems to have been undertaken but it is shown theo-retically"'1 that, for a certain one-dimensional model of a hydrogenbond, the structure of Stokes and anti-Stokes components shouldbe similar.

(3) Structural problems. Several structural questions havebeen investigated by vibrational spectroscopy. These include theconjugation of a cyclopropane ring with a benzene ring,"' themolecular structure of cyanamide derivatives' 4' and the establish-ment of Td symmetry for crystalline arsenic oxide14' Two shortpapers"'14' deal with characteristic frequencies and absorptionintensities of the hydroperoxide group: not much significanceattaches to the force constants found, owing to their large numberand to the artificial decoupling of the hydroperoxide group fromthe rest of the molecule; but the conclusions reached aboutintensities are stated with appropriate caution. There is alsoinfrared spectroscopic evidence for an intramolecular hydrogenbond in isopropyl benzene hydroperoxide."'

Some reassignments in simple molecules have been suggested.For SO3, according to thermodynamic considerations,"' thelowest infrared fundamental should be (440:-30) cm-", indicatinga reinvestigation of the spectrum in this region. Krasnov' 4' favors150 cm-1 rather than 120 cm-1 for the T1I fundamental. Theuniqueness of the conclusion that the interbond angle in HOCl is113" is criticized and a value of (104+3)0 is preferred.' 4'

Apart from examples of rotational isomerism referred to inTable I, other cases (various hydrocarbons,"14 2,4- and 1,5-hexa-diene,"' 1,2-chlorofluoroethane"O) are examined by measuring thetemperature dependence of the intensity. The energy differencesof rotational isomers of 1,2-chlorofluoroethane are found to be(470±-60) and (60±-40) cal mole-' in the liquid and gas phases,respectively, and the anomaly with the result of 480 cal mole-'for the gas phase, determined earlier"' from the temperaturedependence of the dielectric constant, is not mentioned. Theexistence of a gauche isomer is demonstrated by a microwaveinvestigation."'

(4) Intermolecular interactions. The several diverse studiesdevoted to intermolecular interactions comprise infrared investi-gations of the influence of: anhydrous solvents on nitrates,"'5electron-donating solvents on the CH asymmetric stretch inacetylenens foreign gases on the 4025 cm-1 line of water vapor,"14

interaction between pyridine and water,"55 complex formationbetween urea or thiourea and stannic halides,"56 solvents on thecarbonyl frequency'" 7; and Raman investigations of the influenceof solvent type and concentration on the symmetric stretch of thenitro group,"' intermolecular interaction on linewvidth,"' solventon the Fermi doublet of CC14,' 59,5 " and high pressure.

Acknowledgmnent. The author wishes to thank Dr. K. H. Illingerfor helpful discussions concerning the temperature dependenceof spectral intensities.

* The research reported in this paper has been sponsored by the Elec-tronics Research Directorate of the Air Force Cambridge Research Labora-tory, Air Research and Development Command.

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V. T. Aleksanian, Optics and Spectroscopy 6, 66 (1959). (b) A. M. Prima,Optics and Spectroscopy 9, 236 (1960).

' Yu. Va. Gotlib, Optics and Spectroscopy 7, 191 (1959); 9, 166 (1960).9 L. M. Sverdlov, Optics and Spectroscopy 8, 17, 129 (1960)."ON. I. Zhirnov, Optics and Spectroscopy 9, 385 (1960).u R. R. Shvangiradze and Sh. Z. Jamagidze, Optics and Spectroscopy 8,

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109

12 L. S. Mayants, Optics and Spectroscopy 8, 102 (1960).'3 B. L. Livshits, Optics and Spectroscopy 10, 73 (1961)."14 G. A. Khachkuruzov, Optics and Spectroscopy 6, 294 (1959)."15 S. Sundaram, F. Suszek, and F. Cleveland, J. Chem. Phys. 32, 251

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39 L. M. Sverdlov and N. 1. Prokof'eva, Optics and Spectroscopy 7, 363(1959)."40 L. M. Sverdlov and N. I. Prokof'eva, Optics and Spectroscopy 9, 97(1960).

41 R. S. Lebedev, Optics and Spectroscopy 6, 211 (1959)."42 L. M. Sverdlov and F. N. Krainov. Optics and Spectroscopy 6, 214(1959)."4 See reference 10.

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(1961)."6I. M. Mills, W. B. Person, J. R. Scherer, and B. Crawford, J. Chem.Phvs. 28, 851 (1958)."2 L. M. Sverdlov, Optics and Spectroscopv 10, 76 (1961)."63 L. A. Gribov, Optics and Spectroscopy 8, 404 (1960)."6 L, A. Gribov, Soviet Phys.-Doklady 4, 843 (1960).

SS. M. Ferigle and A. Weber, Can. J. Phys, 32, 799 (1954)."1 B. N. Snegirev and M. A. Kovner, Optics and Spectroscopy 8, 462(1960)."V . A. Gribov, Optics and Spectroscopy 9, 346 (1960)."68 L. M. Sverdlov, Optics and Spectroscopy 9, 21 (1960)."69 L. M. Sverdlov, Optics and Spectroscopy 9, 353 (1960).

70 M. A. Kovner and B. N. Snegirev, Optics and Spectroscopy 7, 309(1959).

71 M. A. Kovner and B. N. Snegirev, Optics and Spectroscopy 9, 90(1960).

"7 T. Yoshino and H. I. Bernstein, J. Mol. Spectroscopy 2, 241 (1958).73 A. M. Bogomolov, Optics and Spectroscopv 9, 162 (1960).7' F. A. Savin and 1. 1. Sobel'man, Optics and Spectroscopy 7, 435 (1959).'5 F. A. Savin and I. I. Sobel'man, Optics and Spectroscopy 7, 439 (1959).76 I. I. Kondilenko, P. A. Korotkov, and V. L. Strizhevskii, Optics and

Spectroscopy 9, 13 (1960).7' G. Placzek. Handbu-h d. Radiologie 6, (2), 205 (1934).

78 M. P. Lisitsa, V. L. Strizhevskii, Optics and Spectroscopy 10, 23(1961)."7 B. I. Stepanov and V. P. Gribkovskfi, Soviet Phys.-Doklady 3, 781(1958).

8' M. P. Lisitsa, V. N. Malinko, Optics and Spectroscopy 6, 450 (1959).S1 P. A. Bazhulin, V. N. Smirnov, Optics and Spectroscopy 6, 485 (1959)."82 V. N. Smirnov, P. A. Bazhulin, Optics and Spectroscopy 7, 123 (1959)." M. P. Lisitsa, V. L. Strizhevskii, Optics and Spectroscopy 7, 305 (1959)."81 M. P. Lisitsa, hu. P. Tsyashchenko, Optics and Spectroscopy 9, 389

(1960)."s1 B. L. Crawford and H. L. Dinsmore, J. Chem. Phys. 18, 983 (1950)."86 B. L. Crawford and H. L. Dinsmore. .. Chem. Phys. 18, 1682 (1950)."87 K. H. Illinger and C. P. Smyth, J. Chem. Phvs. 35, 400 (1961)."8s K. H. Illinger and D. E. Freeman (to be published).89 International Commission on Molecular Spectroscopy, Optics and

Spectroscopy 7, 179 (1959)."j0J. Morcillo, J. Herranz, and J. F. Biarge, Spectrochim. Acta 15, 110(1959).

January 1962

TECHNICAL NOTES

"91 B. L. Crawford, J. Chem. Phys. 29, 1042 (1958)."92 V. M. Pivovarov, Va. S. Bobovich, Optics and Spectroscopy 6, 160(1959)."93 A. I. Sokolovskaya and P. A. Bazhulin, Optics and Spectroscopy 8,203 (1959).

94 A. I. Sokolovskaya, Optics and Spectroscopy 9, 307 (1959)."9P P. A. Bazhulin and Yu. A. Lazarev, Optics and Spectroscopy 8, 106(1960)."96 N. I. Rezaev and A. S. Andreev, Optics and Spectroscopy 7, 72 (1959)."97I. L. Mador and R. S. Quinn, J. Chem. Phys. 20, 1837 (1952)."98 N. E. Gapanova, M. P. Lisitsa, hu. P. Tsyashchenko, Optics andSpectroscopy 8, 245 (1960).

99 M. P. Lisitsa and hu. P. Tsyashchenko, Optics and Spectroscopy 6,396 (1959)."100 P. N. Schatz, S. Maeda, J. L. Hollenberg, and D. A. Dows, J. Chem.Phys. 34, 175 (1961)."1W1 1. P. Lisitsa and hu. P. Tsyashchenko, Optics and Spectroscopy 9, 99(1960).

10' (a) M. P. Lisitsa and Vu. P. Tsyasichenko, Optics and Spectroscopy9, 229 (1960). (b) G. S. Denisov, ibid. 7, 119 (1959)."103 W. B. Person, J. Chem. Phys. 28. 319 (1958).

'01 M. P. Lisitsa, Yu. P. Tsyashchenko, Optics and Spectroscopy 10, 79(1961).

105 M. P. Lisitsa, V. N. Malenko, and I. N. Khalinmonova, Opticsand Spectroscopy 7, 386 (1959).

10' V. N. Smirnov, Optics and Spectroscopy 7, 302 (1959).107 A. 1. Sokolovskaya and P. A. Bazhulin, Izvest. Akad. Nauk. S.S.S.R.

er. fig. 22, 1068 (1958)."'s A. D. Buckingham, Proc. Roy. Soc. (London) A248, 169 (1958)."109 V. M. Pivovarov, Optics and Spectroscopy 6, 60 (1959); 9, 139 (1960)."'°A. I. Sokolovskaya and S. G. Rautian, Optics and Spectroscopy 6,

29 (1959)."' D. G. Rea, J. Opt. Soc. Am. 49, 90 (1959).'12 Va. S. Bobovich and T. P. Tulub, Optics and Spectroscopy 6, 362

(1959); 9, 392 (1960)."'1 A. V. Rakov, Optics and Soectroscopy 7, 128 (1959)."'4 Va. S. Bobovich and T. P. Tulub, Optics and Spectroscopy 9, 352(1960)."'1 N. G. haroslavsky and A. N. Terenin, Doklady Akad. Nauk. S.S.S.R.

66, 885 (1949)."116 R. P. Eischens and W. A. Pliskin, Advances in Catalysis 10, 1 (1958)."17 V. Crawford, Quart. Rev. 14, 378 (1960).18 V. N. Filiminov, Optics and Spectroscopy 1, 450 (1956)."n1 V. N. Filiminov and A. N. Terenin, Doklady Akad. Nauk. S.S.S.R.

109, 982 (1956)."'10 V. N. Filiminov, D. S. Bystrov, and A. N. Terenin, Opticsand Spectros-copy 3, 480 (1957)."' L. M. Roev, V. N. Filiminov, and A. N. Terenin, Optics and Spectros-copy 4, 328 (1958)."'2 A. N. Terenin and L. M. Roev, Optics and Spectroscopy 7, 447 (1959)."12 A. N. Terenin and L. If. Roev, Spectrochim. Acta 15, 946 (1959).

124 A. N. Sidorov, Optics and Spectroscopy 8, 424 (1960).12' V. A. Nikitin, A. N. Sidorov, and A. V. Karyakin, Zhur. fiz. Khim. 30,

117 (1956)."'1 R. S. McDonald, J. Phys. Chem. 62, 1168 (1958).'27 A. AT. Bogomolny and hu. A. Lyubimov, Optics and Spectroscopy 8,

131 (1910).12' A. A. Petrov and T. V. Yakovleva, Optics and Spectroscopy 7, 479

(1959)."121 E. V. Shuvalova, Optics and Spectroscopy 6, 452 (1959)."'0 M. 0. Bulanin, G. S. Denisov, and R. A. Puskina, Optics and Spectros-copy 6, 491 (1959).

'5' A. A. Spurr and H. F. Byers, J. Phys. Chem. 62, 425 (1958).us2 R. C. Lord, B. Nolin, and H. D. Stidham, J. Am. Chem. Soc. 77, 1365

(1955).u3s M. A. Bulanin, G. S. Denisov, and D. N. Shchepkin, Optics and

Spectroscopy 7, 119 (1959)."134 Va. 1. Ryskin and G. P. Stavitskaya, Optics and Spectroscopy 7, 488(1959); 8,320 (1960)."'35V. A. Kolesova and Va. I. Ryskin, Optics and Spectroscopy 7, 165(1959)."1'3 Va. I. Ryskin, Optics and Spectroscopy 7, 177 (1959).

1'7 G. P. Stavitskaya and Va. 1. Ryskin, Optics and Spectroscopy 10, 172(1961).

"Is L. N. Ovander, Optics and Spectroscopy 8, 252 (1960)."' V. T. Aleksanian, Kh. E. Sterin, ML. hu. Lukina, I. L. Safonova, andB. A. Kazanskii, Optics and Spectroscopy 7, 114 (1959)."140 B. L Sukhorukov and A. I. Finkel'shtein, Optics and Spectroscopy 6,414 (1959); 7, 393 (1959); 9, 24 (1960).

141 N. N. Sobolev and V. P. Cheremisinov, Optics and Spectroscopy 9,233 (1960).

142 M. A. Kovner, A. V. Karyakin, and A. P. Efimov, Optics and Spectros-copy 8, 64 (1959)."143 L. A. Gribov and A. V. Karyakin, Optics and Spectroscopy 9, 350(1960)."'4 V. V. Zharkov and N. K. Rudnevskii, Optics and Spectroscopy 7, 497(1959)."15 G. A. Khachkuruzov, Optics and Spectroscopy 8, 19 (1960).

146 K. S. Krasnov, Optics and Spectroscopy 7, 494 (1959).'47 L. V. Gurvich and M. M. Novikov, Optics and Spectroscopy 7, 70

(1959)."'48 K. H. Kesler, Yu. A. Pentin, E. G. Treshchova, and V. M. Tatevskii,Optics and Spectroscopy 7, 195 (1959).

14 hu. A. Pentin, hu. N. Panchenko, and F. G. Treshchova, Optics andSpectroscopy 10, 29 (1961)."'0 P. A. Bazhulin and L. P. Osipova, Optics and Spectroscopy 6, 406(1959)."151 A. D. Giacomo and C. P. Smyth, J. Am. Chem. Soc. 77, 1361 (1955)."15 I. A. Mukhtarov, Optics and Spectroscopy 6, 168 (1959)."'5 A. I. Sokolovskaya and S. G. Rautian, Optics and Spectroscopy 6, 29(1959)."1'4 K. P. Vasilevsky and B. S. Neporent, Optics and Spectroscopy 7, 353(1959).

'15 A. N. Sidorov, Optics and Spectroscopy 8, 24 (1960),

'56 D. S. Bystrov, T. N. Sumarokova, and V. N. Filimonov, Optics andSpectroscopy 9, 239 (1960)."'.7 T. V. hakovleva, A. G. Maslennikova, and A. A. Petrov, Optics andSpectroscopy 10, 64 (1961).

1'5 V. M. Pivovarov and N. D. Ordyntseva, Optics and Spectroscopy 6,403 (1959)."69M. P. Lisitsa and L. A. Ovander, Optics and Spectroscopy 7, 383(1959)."'60 V. L. Strizhevskii, Optics and Spectroscopy 8, 86 (1960).

Western Spectroscopy Conference

The Ninth Annual Western Spectroscopy Conference will beheld at Asilomar, Pacific Grove, California, on Thursday andFriday, January 25 and 26, 1962. As in previous years, the programwill consist of invited speakers who will discuss a wide range oftopics of interest to spectroscopists during two morning and twoafternoon sessions. Additional information on this conference canbe obtained by writing to Dr. Donald G. Rea, Chairman, WesternSpectroscopy Association, University of California, Space SciencesLaboratory, Room 3, Leuschner Observatory, Berkeley 4, Cali-fornia, or to Mr. Jackson M. Gordon, Recorder and Registrar,Western Spectroscopy Conference, Shell Development Company,Emeryville, California.

Speakers on Physics for Student SectionsAs a part of its program to interest college students in taking

up physics as a career, the American Institute of Physics hascontacted industrial research laboratories to ask whether membersof their staffs would be available as speakers for Student Sections.The response has been impressive. Many of our own corporationmembers have indicated their willingness to cooperate in thisimportant project, as follows:

American Optical CompanyBaird-Atomic, Inc.Bausch & Lomb, Inc.Bell & Howell CompanyBell Telephone LaboratoriesThe Bendix CorporationCorning Glass WorksE. I. duPont de Nemours & Company, Inc.Gruman Aircraft Engineering CorporationInternational Business Machines CorporationPerkin-Elmer CorporationPolaroid CorporationXerox Corporation

Student Sections may obtain the complete list together withdetailed information on how to arrange for a speaker by writingto Mrs. Ethel E. Snider, National Secretary, Student Sections,American Institute of Physics, 335 East 45th Street, New York 17,New York.

Movies and Film Strips for Student SectionsIn its latest (October, 1961) revised list of movies and film

strips on various branches of physics available to Student Sections,the American Institute of Physics includes two of particularinterest to students of optics:

Crystals (25 min., 16-mm color and sound): This film gives anexcellent discussion of the structure and properties of crystals.The symmetries of crystals are described and the role that sym-metries play in determining various physical properties (e.g.,magnetic properties) is discussed. Showing of the film, alongwith a discussion period, offers a worthwhile program for aStudent Section meeting.

Similarities in Wave Behavior (30 min., black and white, 16-mmsound) : This is an excellent description of the various propertiescommon to all wave motion. The apparatus used to demonstratethese properties is ingenious. One of the most notable featuresof the film is the unification of the various fields of physics wherewaves and wave propagation play an important role.

110 Vol. 52

NECROLOGY

These films may be obtained by Student Sections from the BellTelephone Company by writing to the nearest Bell Telephoneoffice. There is no charge for rental, but return postage for thefilm must be paid by the Section. Allow a month lead time inscheduling.

Personalia

Georg H. HassGeorg H. Hass, one of our associate editors, currently chief of the

Physics Research Laboratory of the U. S. Army Engineer Researchand Development Laboratories, Fort Belvoir, Virginia, is therecipient of one the first Army Research and DevelopmentAchievement Awards established by Lt. General Arthur G.Trudeau, Chief of Research and Development, Department of theArmy. Dr. Hass was cited for his research on the optical propertiesand applications of evaporated films, applications of surfacecoatings for controlling the temperature of satellites, and studiesof the optical properties and oxidation of metals.

Technical Calendar

1962January

10-12 Tenth annual seminar, sponsored by College of Engi-neering and Southeastern Association of Spectrog-raphers (SEAS), University of Florida, Gainesville,Florida

22-25 68th Annual Meeting, American Mathematical Society,Sheraton-Gibson Hotel, Cincinnati, Ohio

22-26 31st Annual Mid-Winter Convention in Ophthalmologyand Otolaryngology, Statler Hilton Hotel, LosAngeles, California

24-27 American Association of Physics Teachers, Annualmeeting, New York City

24-27 American Physical Society, New York City25-26 Ninth Annual Western Spectroscopy Conference,

Asilomar, Pacific Grove, California

February23-24 American Physical Society, Austin, Texas

Kfarch5-9 Thirteenth Pittsburgh Conference on Analytical Chem-

istry and Applied Spectroscopy, Penn-SheratonHotel, Pittsburgh, Pennsylvania

12-13 Inter-Society Color Council, Statler-Hilton Hotel, NewYork City

14-17 Optical Society of America, Mayflower Hotel, Washing-ton, D. C.

28-31 Third Symposium on Spectroscopy, sponsored by Hy-drocarbon Research Group of the Institute of Petro-leum, University of London

A pril16-19 International Conference, Vacuum Ultraviolet Radia-

tion Physics, University of Southern California29-May 4 91st SMPTE Convention with Equipment Exhibit,

Ambassador Hotel, Los Angeles, California30-May 3 13th Annual Mid-America Spectroscopy Sympo-

sium, Conrad Hilton Hotel, Chicago, Illinois

Necrology

Monroe Hamilton Sweet

Monroe H. (Gus) Sweet died September 8, 1961 in the crash ofhis private plane at Green, New York.

A 1937 graduate of Wesleyan University, Mr. Sweet worked forthe Weston Electrical Instrument Corporation as a sales engineerbefore joining Ansco in 1939 as a physicist in the Research andDevelopment Department. During his fifteen years with Ansco,he became a recognized authority in the fields of photographicdensity measurement and photometric instrumentation and hadto his credit more than twenty U. S. patents. He joined ourSociety in 1941 and is perhaps best known to our members forhis development of the Ansco-Sweet densitometer.

In the late 40's Mr. Sweet became an ardent pilot and soonbegan work on an automatic control device which was patentedand marketed as the Anscopilot. He left Ansco in 1955 to form hisown company, Navigation Devices, Inc., to conduct research anddevelopment work in aviation electronics, and shortly thereafteralso formed Quantametric Devices, Inc., for the design anddevelopment of special photometric equipment for photographicmanufacturers and various government agencies. At the time of hisdeath, Mr. Sweet was president of both companies.

Besides his membership in the Optical Society of America, hewas a Fellow of the Photographic Society of America and amember of the Society of Photographic Scientists and Engineers.He was active in the work of the American Standards Associationand the Inter-Society Color Council.

His loss is keenly felt among all those who knew him andassociated with him in the several fields of his scientific work.

May29-June 19 World Meteorological Organization, executive

committee session, Geneva, Switzerland

June18-22 International Conference on Spectroscopy, College

Park, Maryland

July8-14 Sixth International Congress on Glass, Washington,

D.C.16-20 International Conference on The Physics of Semi-

conductors, University of Exeter, Exeter, England

August19-26 Sixth Conference of International Commission for

Optics, Munich, Germany21-24 Far Infrared Spectroscopy, International Symposium

sponsored by Wright Air Development Division,Materials Center, Sheraton-Gibson Hotel, Cincinnati,Ohio

21-28 International Congress on Acoustics, Copenhagen,Denmark

27-30 American Astronomical Society, Yale University, NewHaven, Connecticut

29-Sept. 5 International Congress of Electron Microscopy,Philadelphia, Pennsylvania

October

3-6

15-19

Optical Society of America, Manger Hotel, Rochester,New York

Instrument Society of America, international con-ference and exhibit, New York, New York

IIIJanuary 1962