SPIE Proceedings [SPIE SPIE Proceedings - (Sunday 12 February 2012)] - Continuous chemical lasers...

Continuous chemical lasers of visible region.

A.N.Dvoryankin

Department of optics, P.N.Lebedev Physical InstituteI 17924, Moscow, Leniasky prospekt, 53. Tel. 1358773

1. Introduction.Now powerful lasers of 1W region on electronic transitions of excimer molecules1 RX*,RR$ where R is

rare—gas atom and X — halogen, are created. Emitting molecules are produced during chemical reactionsbetween electronically excited (EE) atoms R and halogen—containing molecules. To generate EE atoms Rpowerful pumping sources are used such as e—beams, electric discharge or short—wavelength radiation. Anactual problem is the creation of chemical short—wavelength lasers, in which EE radiating particles aregenerated as the result of chemical reactions, started by reagents in ground electronic states. Today the onlyexisting chemical laser on electronic transitions is oxygen—iodine one, with wave—length X1,315 tm.Extension to visible wavelength causes many problems because it requires an essential increase of pumpingrate. Discussing some general features of short wavelength chemical lasers (SWCL) it may be useful toconsider the parameters, determining small signal gain, which is a product of stimulated emission crosssection times inversion density. Stimulated emission cross section is proportional and population inversiondensity is usually inversely proportional to Einstein coefficient zN"W/A, where W is pumping rate. Thereforegain coefficient is independent2 from A. So, it is convenient to write the dependence of stimulated emissioncross section on parameters of emission spectra in the form:

u=(x2A/8)pzi(g/W)A (1.!)

where A—wavelength and p is normalized line shape function, g means some "threshold" value of gaincoefficient and may be taken g103cm', then W nieans some characteristic pumping rate, depending onwavelength and emission line shape.

W8irg/(A2p) (1.2)

w• is proportional to effective width of the emission. For Doppler atomic line one can obtain

W8=575.(T/M)'/2/x3 (1.3)

where T — temperature (K), M — mass (AMU).For a single emission line v'J'—v"J" in a diatomic molecule it is necessary to account for distribution of

electronically—excited level population over many vibrational and rotational sublevels2. For the thermalizedrotational distribution

W'56O.T/E(M)1/2fq,A31 (1.4)

In (1.4) q,—Franck—Condon factor, f',, fraction of population at the upper vibrational level, B is rotationalconstant in cmt. W', for diatomic molecules is typically three orders of magnitude higher than for atoms.

For broad spectra of excimer complexes Wc can be estimated as

W=O.O25v/X2 (1.5)

where Au is width of the emission peak.One can see from (1.3., 1.4) that characteristic pumping rate scales as X, assuming other parameters

constant. So in order to achieve equal gain coefficient for two times shorter wavelength it is necessary toincrease pumping rate eight times.

Chemical pumping rate depends on reagent concentrations as WkEAJEBJ so minimal initial reagent

SPIE Vol. 1397 Eighth International Symposium on Gas Flow and Chemical Lasers (1990) / 145

Downloaded From: http://proceedings.spiedigitallibrary.org/ on 09/06/2013 Terms of Use: http://spiedl.org/terms

concentrations and time of inversion existence are

EAi0EB10=(W/k)'/2 (1.6); (1.7)

2. Electronic energy transfer pumping of short—wavelength chemical lasers.

Early attempts in developing (SWCL) were concentrated on direct schemes of pumping, when emittingparticle is produced at the first stage of chemical reaction. These are recombination3 and metal atomoxidation4 lasers.

Subsequent investigations shows, that the branching ratio of EE states production in chemical reaction issmall for these states which are connected with the ground state by allowed radiative transition.Simultaneously success in the development of chemical oxygen—iodine laser has attracted attention ofinvestigators to electronic energy—transfer (EET) schemes of pumping, when produced in chemical reaction EEmetastastable particle — donor transfers its energy to the emitting particle — acceptor in collisions.The spinof metastable EE particles usually differs from the spin of the ground state.The branching ratio of theirproduction in chemical reaction is high, when ground state production is forbidden by the spin and angularmomentum correlation rules6.

Long radiative lifetimes of EE metastable particles and small values of quenching rate constants makethem suitable candidates for the role of energy donors for EET lasers.

According to the structure of their outer electronic shell EE particles may be divided into two groups7. Thefirst includes EE particles, which have the same electronic configuration as the ground state. In the groundstate such particles have degenerate partially filled highest occupied orbital with more than one electron andmore than one vacancy (N(2p3—4S), O2(fl2gX3Eg)). In this case the lowest EE states differ from the groundstate in the scheme of spin and angular momentum coupling, but have the same orbital structure (N(2p3—2D),

02(2g1g)) Energies of such EE states are relatively low (see tab.!). The second group includes EE particleswhich have electrons on the unoccupied in the ground state orbitals (N2(1n3uhr'gA3Eu)). As usual theseparticles have higher excitation energies.

Tab 1 .Electronic configurations, energies and radiative lifetimesof electronically excited particles8

particle energy (eV) radiative lifetime(s)

O2(2ga' ) 0.98 3.91O

O2(T2b1Eg) 1.64 12

NF(2ii—a'i) 1.42 1.

NF(2ir2—b1E) 2.34 2. 102N(2p3—2D) 2.38 6. iO

N2(13u3a2gfl'gA31) 6.2 1.3

The essential difference between particles belonging to these groups lies in mechanism of their interactionwith other particles during collisions.

Exchange interaction of the first group particles colliding with the particles, which have closed electronicshell is usually repulsive. So, the main mechanism of NF(a),02(a) quenching is quasiresonantelectronic—to—vibrational energy transfer91t with small rate constants.

The equilibrium distances for EE molecules of the first group are nearly equal to equilibrium distances ofthe ground states. So, during electronic transition all electronic excitation energy can be transferred to theacceptor. Therefore searching for acceptors one have to choose those with EE states which are in resonancewith energies of donors of the first group.

The particles of the second group can easily give an electron from the excited orbital or receive anelectron in the vacancy on the low—lying orbital. In this case their exchange interaction will have ionic

146 / SPIE Vol. 1397 Eighth International Symposium on Gas Flow and Chemical Lasers (1990)


character and be attractive. Because of different orbital structure, equilibrium distances for EE states of thesecond group molecules differ from equilibrium distances of the ground states. According to Franck—Condonprinciple vertical transitions are favored. So, EE molecule N2(A,v0) can easily give only 4—5 ev of totalexcitation energy 6,2 ev, which corresponds to N2(A,v'0—X,v"4—7) transitions. Therefore N2(A) quenching israpid if quenchers have EE states with excitation energies lower than 5 ev (k dOb0_!Oh1 cm3/s), but is verys1ow1213 (k<1O'5cm3/s), for the quenchers without EE states lying lower t'lian 6,2 ev. Looking for acceptorsfor the EE donors from the second group it is necessary to choose particles with EE states lying lower thanenergies of vertical electronic transitions for corresponding donors.

In order to create EET laser, high concentrations of EE donors should be produced. Therefore selfquenchingof donors is most important. Corresponding rate constants are listed in tab.2.

TAB.2. Selfquenching processes for metastable particles.

Process k(cm3/s) Ref.

O2(a)+O2(a)-O2(b)+O2(X) 2(—17) 13

NF(a)+NF(a)—products 5(—12) 10

N2(A)+N2(A)-'N2(B,C)+N2(X) 3(— 10) 21

Due to their electronic structure the first group donors are more stable to quenching and selfquenching,but they have lower energies, so it is necessary to use two— or three— step schemes of pumping7 in order tocreate a visible range EET laser using these donors. Two step pumping of Bir(a) by NF(a)'5 and IF'(B) by02(a)'6 was considered but the kinetic of these media is not clear enough

The second group donors have sufficient energy to pump emitting in visible region particles in onecollision, but the processes of their quenching and selfquenching may cause many problems.

Very promising is the usage of N2(A) as a donor, and IF molecule as lasing particle'7'9. IF is excited in thecollisions with N2(A):

N2(A3E)+IF(X'E1) ., IF(B3n0+) +N2(X'E)

The rate constant of this process is great20: k=2100cm3/s and the quantum yield of IF(B) is more than0.4 . Estimations based on formulas (1.4—1.7) show that the threshold pumping rate to achieve gain g=103 onIF(B,v'z0—X,v"5) transition (x=625 nm ) is W1019cm3s1, while concentration of IF(X) should be nothigher17 than 1016 cm3 in order to prevent fast selfquenching. To achieve such pumping rate concentrationof N2(A) should be higher than 1013cm3. The time of population inversion existence will be of order 310.Therefore in gas flow lasers it is necessary to use supersonic flow to achieve inversion zone of few cm.

3.The possibility of N2(A) — IF laser creation.

Much attention is devoted to 112—F—HN3 and H2—F—NF2 flames as chemical sources for pumping SWCL.During chemical reactions in these media metastables — long lived electronically excited atoms and moleculesare effectively generated, among them N2(A).

The main processes which determine the kinetics of electronically excited particles in H2—F—Nl!2 andH2—F—HN3 flames and lead to N2(A) formation are listed in our paper.

Numerical modeling of these flames was done24 and the possibility of usage of these flames as pumpingsource for N2(A)—IF EET laser was shown.

The gas flow was calculated in one—dimensional approximation of gas—dynamics, supposing simultaneousmixing of components in the supersonic part of the nozzle. Divergent nozzles were considered in order tolimit temperature growth. Initial chemical composition was varied in order to achieve maximal gain. The gainof 0.2—0.3m1 was calculated24 for the initial pressure p150 torr in a highly divergent nozzle, themaximal temperature was 400 K. The results of the calculations for the nozzle with lower divergence andlower initial pressure are shown on Fig 1,2. Relative area of the nozzle at X0, 1 and 5 cm was 50:51:55=1:1,5:3



and initial pressure P35 torr.Fig. I shows for the H2—F—NF2 flame the dependences af temperature and gain coefficient on the distance

x from the mixing pointInitial chemical composition was 86%He+2,5%NF2+6%H2+5%F+O,5%IF. Gain coefficient (full line) achieves it's

maximal value am=O,!5m at the distance of X1.2 cm, while the temperature grows up to Tm66O K.Those dependences for the 112—F—11N3 flame are shown on fig. 2. Initial chemical composition was

89,5%He+2%HN3+2%H2+6%F+O,5%IF. Maximal value of gain coefficient is 0,16 m1, while temperature reachesTm680 K.

So, modeling of 112—F—NF2 and H2—F---HN3 premixed flames shows the possibility of high concentrations ofN2(A) generation in these media in order to use it as energy donor. Although in real devices their lasercharacteristics may become worse as the result of incomplete mixing, these media look like promisingsources for pumping SWCL.

4. Mechanism of light amplification on Na3Br excimer transitions.

In this part of the report the results of the experiments are discussed, in which visible light amplification(A=527nm) was reported'26 by active medium with chemical punping. Supersonic beam of Na:Na2:Na3 wasmixed with the perpendicular flow of Br atoms. Light amplification was measured by a tunable dye laserwhich was directed perpendicularly to both halogen and sodium flows. The authors have explained measuredgain coefficient a2!03 cmt by the population inversion on Na2(BtHu,v6'XtE+g,v114) transition. Theysuggest the following kinetic scheme of population inversion creation:

Na3 + Br !cNa2(B,v',J') + NaBr; Na2(B,v',J') —Na2(X,v",J") + hv; Na2(X,v",J") + Q products

But one can easily obtain that z1 kqEQl frequency of Na2(X,v") quenching should be greater thanwhere A= 1.4 108s1 Einstein's spontaneous emission coefficient for Na2(B—X) transition, — FFC27

for v'6 — v"14,To maintain the population inversion on Na2(B,v',—X,v") transition z1 must be of 2!O order of

magnitude. Upper estimate of quenching rate coefficient is kqa•v6!09cm3/s where u=3!014cm2 andv2 !O cm/s are upper estimates25 of quenching cross section and velocity. Using these values of z and kq weobtain density of quenchers (Br—atoms) EQ13 !015cm3, which is by more than an order of magnitude higherthan any reasonable estimate for the reported conditions (p < !02 Torr).

To explain these results the chemical—excimer mechanism of pumping was suggested

Na3 + Br ———> (Na3Br); (Na3Br) Na2(A,B,C) + NaBr; (Na3Br) A> Na2(X) + NaBr + hiS'

In the fast reaction of Na3 cluster with atomic bromine appears excimer complex (Na3Br) which can breakwhith out radiation or radiate with transition on the repulsive term

In this case the depopulation of lower laser level is fast enough. From (1.5) one can obtain the thresholdpumping rate W=2.5.LO2AVCh/X2, where vCh=2.lO'2s'(AXCh2nm) — is the reported width ofchemiluminescence peak25'26.

In the conditions of the bromine atoms excess pumping rate is limited by the Na3 flux into the amplifyingvolume !=ENa3l.u/d, where u1.5lO5cm/s—velocity of Na3 flow,d0.5cm— diameter of the reaction zone.Assuming that the quantum yield of the excimer luminescence A/(A+z) is near unity it is easy to calculatethat the density [Na3]6 1013cm3 provides the gain coefficient a=!O3cm. This estimate of the Na3 densityis close to the reported25 . Observed spectrum of luminescence25'26 looks like excimer spectrum1. So thereported25'26 gain can be explained by the suggested chemical—excimer mechanism

5.Mechanism of enhancement of the dimole emission of singlet oxygen.

A model is proposed, that explains experimentally observed increase of the dimole emission (DE) of singlet



oxygen. The dimole emission of singlet oxygen is a bimolecular cooperative process

O2(a,v1)+O2(a,v2)-'O2(X,vj)+O2(X,v)+hv (5.1)

of one photon emission in collision of two electronically excited molecules 02(a).The energy of the emittedphoton is close to the sum of energies of electronic excitation of two collided molecules 02(a) and depends onthe difference of the vibrational excitation of the products and reagents of the reaction (1) 7vj+v—(vj+v2).The interest to DE increased after reports3t about observation of visible light amplification (X703nm) andlaser oscillation on the dimole &ansitions of singlet oxygen.

The rate constant of process (1) while collision of vibrationally unexcited molecules 02(a) is extremelysmalI (k=5.!Ocm3/s) and can't explain the intensive DE and light amplification31.

We suppose, that intensity of DE grows due to rapid increase of DE rate constant with increase ofvibrational excitation of colliding molecules 02(a,v).

The foundation of the model is the assumption of the existence of a sufficiently stable excited complex04.The energy barrier for its formation EA is by AE higher than the energy of two electronically—excitedmolecules 2() (see fig.3).The existence of bounded state O'4 was predicted34 on the basis of quantumchemical calculations.The activation energy for the bounded state formation while the collision of twomolecules 02(a) in ground vibrational state is34 AE 15000°K which approximately corresponds to sevenvibrational quanta of 02(a) molecule (m=iE/(hw)s7).That's why in the medium of vibrationally unexcitedsinglet oxygen TT3OOK° the efficient formation of bounded states 04 does not take place and the rateconstant of DE is small.But at high vibrational temperatures T,( 1 —2)103 °K the process of O'4 formation maybe fast enough.

High vibrational temperature in the conditions of experiment 31 can be achieved as the result of 02(a)quenching to vibrationally—excited 02(X,v>O) on the surface of heated tube and rapid VV' exchange processesbetween molecules 02(a) and 02(X).

The following kinetic scheme of the DE enhancement is proposed

O2(a,v1)+O2(a,v2)-÷O (5.2) 02(b)+M—'02(a)+M (5.6)

O&O2(X,v'1)+O2(X,v'2)+hv (5.3) 02(x,v)+M-*02(x,v— !)+M (5.7)

O2(X,v')+O2(a,v)-O2(X,v'— !)+02(a,v + 1) (5.4) O2(a,v)+M-O2(a,v— 1 )+M (5.8)

O2(a)+O2(a)O2(b)+O2(x) (5.5) M02(x),02(a),H20,C12In the reaction (2) the long—lived state O'4 may be formed. The averaged value of k2 depends on the

vibrational temperature T of 02(a) molecules, k2ko2Q2exp(—AE/T8),where Q is vibrational statistical sum andk02 is near gas—kinetic.

In each act of the reaction (2) m=v1+v2 vibrational quanta of 02(a) are absorbed. As the result of thespontaneous emission (3) p=vj+v vibrational quanta of 02(x) are produced. In VY' exchange process (4)vibrational quanta of 02(X) are transferred to molecules 02(a).

Selfquenching of 02(a) and vibrational relaxation of 02(X,v) are relatively slow k5=2.!017cm3/s,k7!O8cm3/s and for vibrational relaxation of 02(a,v) rate constant k8!O13cm/s was reported35.

Equations for stationary distributions of concentrations of vibrational quanta n1=Ev[02(X,v)1, n9=Ev02(a,v)1,complexes 04' and molecules 02(a) look like.

un'x=—k7(n1—n1o)—k4E02(a)1E02(X)1f(a1,a)+pAE04'l+Dn (5.9)

un'8—k8(n—n80)+k4E02(a)JE02(X)1f(a,a,)—mk2g(a5)[02(a)12+Dn (5.10)

uE04'J'—AE04'J+k2g(a)E02(a)J2 (5.11)

u[02(a)l'—(k5+k2g(a8))E02(a)]2+D[02(a)l" (5.12)



In eq. (9—12) prime — means a derivative with respect to space coordinate z along the flow , k1 rate constantsof subsequent processes (2—8) ,u is flow velocity ; D diffusion coefficient

The factor f(a,a1) in equations (9,10) accounts for the dependence36 of VV' exchange rates on meannumbers of subsequent vibrational quanta per molecule 02(X) and 02(a): a1n1/E02(X)1, a8n/[O2(a)l. Factor gin eq.(!O—12) accounts for the dependence of rate constant k2 .on a and may be expressed as

The analysis of eq (9— 1 1 ) shows, that in singlet oxygen as the result of processes (2—4) there is the loop ofcross—catalysis. Increase of vibrationally excited molecules 02(X) leads to production of vibrationally excitedmolecules 02(a) as the result of VV' exchange , and vibrational temperature T8 grows.This leads to theincrease of rates of 04 complex formation and 02(X) vibrational quanta production.Total number ofvibrational quanta grows as the result of these processes. Really,the chemiluminescence spectrum of 04, hasa maximum in 705 nm region, that points out that the average difference y between the number ofvibrational quanta m used for 0*4 formation and the number p of vibrational quanta released as a result ofradiation decay of O4 is positive yp—m!>O (see. fig.3).

Searching for homogeneous along the flow solutions of eq.(9— 12) we come to the equation of total numberof vibrational quanta balance, in which we may neglect the relatively small term describing 02(X) VTrelaxation.

k8102(a)1E021(a8_a80)7k02E02(a)12a8m/( 1 +aa)m+2 (5.13)

Eq.13 means that vibrational quanta release in process of VT relaxation is compensated by their productionas the result of processes (2—4). Equation (13) has several roots. Our estimations show, that first rootcorresponds to relatively low vibrational temperature of singlet oxygen under usual conditions. lint there alsoexist a solution, that corresponds to high value of vibrational excitation. Exact values of k8 and k02 areunknown. Assuming k8=1013cm/s, k02=1O"cm3/s; [02(a)l/[021=O,5 , m=7 we get aaO,4 which correspondsto vibrational temperature T18OO°K .In this case k28.1015cm3/s. The high vibrational temperature will bemaintained as a result of transfer of the part of electronic excitation energy of 02(a) to the vibrationalexcitation of molecules 02(a),02(X) in processes (2—4).

To evaluate of gain coefficient on the dimole transitions (3) we can neglect the population of the lowestrepulsive term

aaEOl(X2/(8ir).k2(T)EO2(a)12/Av 1 ,5 104cm1

(X=705nm,E02(a)131016cm3,Av 1013s1)2931To achieve the gain coefficient w4O3cm1 order of magnitude. the value of the rate constant k2 should

be k2(Ta)i013 cm3/s , In this case all singlet oxygen will be quenched at the distance ofLg=u/(k2EO2(a)])O,3cm which is in contradiction with the reported results31, where the length of thedimole emission was of order few cm.

So , the suggested model can explain experimentally observed31 enhancement of the dimole emission ofsinglet oxygen. A possible value of gain coefficient is evaluated.It is shown that the reported value of gaincoefficient is too high for broad chemiluminescence spectra of the dimole emission.

6. Conclusion.

Problems of continuous—wave short—wavelength chemical lasers creation are discussed. Particular attentionis devoted to H2—F—NF2 and H2—F—HN3 flames as possible sources for chemical pumping of N2(A)—IF laser.

While using molecules as emitting particles it is possible to create population inversion resulting from fastrelaxation of the lower laser level. But high pumping rate is necessary in order to achieve sufficient gainbecause of wide emission spectrum. Atoms as emitters may be used to reduce pumping rate. But the problemof lower laser level cleaning seems still unsolved for atoms, so one can count on creating pulsed lasers usingatoms as lasants37



Q15

0.1

Q05

FIG. 1 Plots of the temperature (broken line) and FIG.2 Plots of the temperature (broken line) andgain (full line) for the 112—F--NF2 flame. gain (full line) for the 112—F—11N3 flame.

E• 4Ocm

20

\Eo)'15

'to.

ç) 02(x)+02(x)

FIG.3 The scheme of 04 potential energy surface.

REFERENCES

1. "Excimer lasers." Ed.Ch.K.Rhodes, Springer—Verlag, 1979.2. V.A.Kochelap, S.I.Pekar ."Theory of spont.aneous and stimulated chemiluminescence of gases.", Naukova

Dumka, Kiev, 1986.3. A.S.Bashkin, A.N.Oraevsky ."On the problem of continuous—wave recombination lasers creation." Kvant.

Elektr., v.3, pp.29—44, 1976.4. W.W.Rice ."Metal atom oxidation lasers a new family of chemical lasers". IEEE J.Quant. Electr.

v.QE—1 1,pp.689—69O, 1975.5. Y.C.Hsu, J.G.Pruett ."Nascent metastable products in the reaction Ba+N02 and Ba+N20 .", LChem.Phys

v.76,pp.5849—5855, 1982.6. R.L.Flurry ."Symmetry groups. Theory and Chemical Applications", Mir, Moscow, 1983.7. V.F.Gavrikov, A.N.Dvoryankin, A.A.Stepanov, A.K.Shmelev, V.A.Shcheglov. "Chemical lasers of visible and

near IR region" Proc.P.N. Lebedev Physical Institute. v.194, pp.17l—21l, 1989.8.A.A.Radzig, B.M.Smirnov. "Handbook on atomic and molecular physics." Moscow, Atomisdat, 1980.9. A.N.Dvoryankin, LB.Ibragimova, Yu.A.Kulagin, LA.Shelepin. "The mechanisms of electronic relaxation in

atomic—molecular media". Himiya Plasmy, Ed.B.M.Smirnov, Moscow, Energoatomisdat, v.14,pp.102— 126, 1987.10. R.P.Wayne. "Singlet Oxygen." Ed.A.A.Frime. CRC Press, Cleveland, 1984.1 1. K.Y.Du,D.W.Setser. "Quenching rate constants of NF(a'A) at room Temperature" J.Phys.Chem, v.94,

pp.2425—2435, 1990.12. M.F.Golde "Reactions of N2(A)." Int.J. of Chem.Kinet. v.20,pp.75—92, 1988.13. D.Z.Cao, D.W.Setser ."Excitation transfer reactions of N2(A) to SO and other diatomic and polyatomic

SPIE Vol. 1397 E/ghth International Symposium on Gas Flow and Chemical Lasers (1990) / 151

AE


molecules". .LPhys.Chem. v.92, pp.1169—1176, 1988.14.P.M.Borrel, K.R.Grant, M.D.Pedly ."Rate constants for energy—pooling reactions of singlet molecular

oxygen at high temperatures." J.Phys.Chem. v.86, pp.700—703,1982.15. J.M.llerbelin ."Short—wavelength laser development". Proc. Lasers—87. Ed.F.J.Duarte. P.218—222, McLean,

STS Press, 1988.16. S.J.Davis, A.M.Woodward. "State selective chemiluminescent reactions for chemical laser applications".

Ed. J.C.Whitehead ."Selectivity in chemical reactions.",pp.457—513, 1988.17. N.G.Basov,A.N.Dvoryankin, V.A.Shcheglov. "Chemical generation of electronically excited molecular

nitrogen N2(A,B).Possibility of developing an exchange N2(A)—IF visible band (x625 nm) laser. Journal ofSoviet Laser Research.v.10,pp. 104—122, 1989.

18. V.A.Kochelap, l.A.Izmailov, L.Yu.Melnikov. "The possibility of population inversion and light gain due toelectronic energy transfer from N2(A3E)." Chem. Phys. lett., v.157. P.67—76, 1989.

19. N.G.Basov, V.F.Gavrikov, V.A.Shcheglov." Energy transfer chemical lasers of visible and near IR region onelectronic transitions of halogens and interhalogens." Kvant. Elektr.(Sov.), v.14,pp. 1754—1771, 1987.

20.L.G.Piper, W.J.Marinelly, W.T.Rawlins, B.D.Green. "The excitation of IF(B3n0) by N2(A3E)". J.Phys.Chem.v.R. pp.602—80Q, 1QR.

21. L.G.Piper. "State—to—state N2(A) energy—pooling reactions I. The formation of N2(C3ll) and Hermaninfrared system". J. Chem. Phys., v.88.Ni. pp.231—239, 1988.

22.A.N.Dvoryankin, V.N.Makarov. "Chemical generation of electronically excited nitrogen N2(A) and lasers onelectronic transitions." Proc. 8th GCL.

23. A.N.Dvoryankin,Yu.A.Kulagin,V.N.Makarov, V.A.Shcheglov. "The possibility of visible range lasers creationon H2—F—NF2 flames " Kratkie soobschenia po fizike (Sov.),N1,pp3—5,1990.

24. A.N.Dvoryankin, V.N.Makarov, V.A.Shcheglov. " Comparison of active media of visible rknge chemicallasers on H2—F—NF2 and 112—F—HN3 flames " Kratkie soobschenia po fizike (Sov.),N1,pp6—8,1990.

25. S.H.Cobb, J.R.Woodward, J.L.Gole. "A chemical process producing a continuous laser amplifier in thevisible region". Chem.Phys.Lett., v.143, pp.205—213, 1988.

26. S.H.Cobb, J.R.Woodward, J.L.Gole. "Conlinuous chemical amplification of single and multi—mode lasers inthe visible region". Chem.Phys.Lett., v.156, pp.197—203, 1989

27. LDemtroder, W. Stetzenbach, M. Stock. "Lifetimes and Frauck—Condon factors for the B'HuX1Egsystem of Na2". J.Mol.Spectr. v.61, pp. 382—394,1976.

28. A.N.Dvoryankin, V.A.Scheglov. "Chemical pumping and excimer mechanism of light amplification onNa3B? molecule".Kratkie soobschenia po fizike (Soy.), N, pp.20—22, 1989.

29. S.Yoshida, M.Taniwaki, T.Sawano, K.Shimizu, T.Fujoka. "Observation of high laser gain at 703 nm in anew chemical system." Jap. Journ. Appl. Phys.v.28, pp.831—833,1989.

30. S.Yoshida, K.Shimizu, T.Sawano, T.Tokuda, T.Fujoka. "Observation of chemical laser oscillation in thevisible region." Appi. Phys. Lett. v.54, pp.2400—2401,1989.

31. S.Yoshida, T.Tokuda, K.Shimizu. "New emission spectra from oxygen." Appl.Phys.Lett. v.55,pp.2207—2708,1989.

32. R.Boodaghians, P.M.Borrel, P.Borrel, K.R.Grant. "Intensities of hot bands in the dimole emission ofsinglet molecular oxygen 02(a'Ag)." J.Chem.Soc.Farad.Trans.2., v.78, pp.1195—2003,1982.

33. A.N.Dvoryankin. "The mechanism of light amplification on the dimole transitions of singlet oxygen."Kratkie soobsheniya po fisike(Russ.). N5,1990.

34. V.Adamantides, D.Neisius, G.Verllaegen. "Ab—initio study of the 04 molecule." Chem.Phys. v.48,pp.215—220,1980.

35.O.Klais, A.H.Laufer. "Atmospheric quenching of vibrationally excited O2('). J.Chem.Phys., v.73,pp.2696—2699,1980.

36.B.F.Gordietz, A.I.Osipov, L.A.Shelepin. "Kinetic processes in gases and molecular lasers." Nauka, Moscow,1980.

37. S.Rosenwaks. "Novel approach to short—wavelength chemical lasers." J. de Phys., Coll. C7 v.48, pp.339—342, 1987.



Date post:	14-Dec-2016
Category:	Documents
Upload:	maris
View:	214 times
Download:	2 times

SPIE Proceedings [SPIE SPIE Proceedings - (Sunday 12 February 2012)] - Continuous chemical lasers...

Documents