AD-AOBl 776 NAVAL RESEARCH LAB WASHINGTON DC F/B 4/1THE PHYSICS OF THE PHOTODEPOSITION PHASE OF THE NRL MASTER CODE--ETC(U)JAN Ao A A ALI
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Januaryu, 190
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SECURITY CLASSIFICATION OF TIS PAGE (Whiom Pea. 9"1"90___________________
READ INSTRUCTMOSREPORT DOCUMAENTATION PAGE 158Fomz COMPLZrzG FoW1. ~~ GOOT Ueat6VT ACCZSSOMno: 15. RecIilNTs CATALOG NNE
NRL Memorandum Report 4152S.TEOFEPT moCVED
(a HE HYSICS OF THEjHOTODEPO8MONtHASE OF Itrmrpr naculuuTHE Wl. MASTER QpDE FOR THE DISTURBED 5 ND NRL problem
6. PERFORMING 104G. REPORT MUERF EGIONS. __________
9. CONT ACT..f3*MMMSW*~
tO. ROGAM EEMET. PROJECT TASKa. PERFORMING RA4 ANNM N DRS AREA & WORK WUN NU-P9ER5
Naval Research I~~~tr NRL Problem 67-08514)00Washington, DC 20375 DNA Subtask S9gQAXHD411
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Defense Nuclear Agency January 24, 1980 irq -Washington, DC 2005 13. NUMGER Of PAGES
4814. MONITORIM AEUCY NAME S Ofgljf~iLeC..Wmlih office) 15. SECURITY CLASS. (010101 EoCPMf)
UNCLASSIFIED
-Ia. DEC ASSIFICATION(DOWNGRAOING
I0. SUPPLEMENTARY NOTESibis work was performed at the Naval Research Laboratory under the auspices of the DefenseNuclear Agency under subtesk S99QAXHD4 11, work unit title Reaction Rates Essential toPropagation.
19. KEY WORDS (Contilnue ona evere. side It necessay and Idontift 4W Weoek #mbke)
NRL Master CodeE & F RegionThotolonizatiln
20. ABSTRACT (Coninfue on reveres side If notoooy nod Identfy Aw block mmmii.)
- ), The physics of the revised photoionlzatlon phase for the NRL Master Code for the DisturbedE and F Region of the Ionosphere Is presented. The revision utilizes current total and partialphotolonization cross sections.
DD 14n3 EDITION OF I NOV 68 Is OSSOLETES/11 0102-014-6S01 SECURITY CLASSIFICATION OF TWIS Ph"ARS 5fI -01 D ole
~~ j)
CONTENTS
I INTRODUCTION . 1
II PHOTODEPOSITION . ................. 2
III PROTOABSORPTION AND PROTOIONIZATION OF N2 . . . . 7
IV PHOTODISSOCIATION OF N 2.. ............. 13
V PHOTOIONIZATION OF N .............. 16
VI PHOTOIONIZATION OF O ..... .............. ... 24
VII PHOTOABSORPTION AND PROTOIONIZATION OF 02 .... 32
VIII PHOTODISSOCIATION OF 02 ...... ............. 37
REFERENCES . . ....... .................. 41
gm wht swtm
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* I
THE PHYSICS OF THE PHOTODEPOSITION PHASE OF THE NRLMASTER CODE FOR THE DISTURBED E AND F REGIONS
I. INTRODUCTION
The fireball of a high altitude nuclear detonation emits a wide
range of electromagnetic radiation. Among the emitted spectrum, the
ultraviolet and the x-ray radiations dissociate and ionize a vast amount
of the upper atmosphere and generate what is usually called the uv-fire-
ball. The uv-fireball, as an ionized medium, impacts heavily on com-
nmunication, radar, visible and infrared detectors and other systems of
interest. Therefore, it is of considerable interest to predict the
ionization and the deionization of the uv-fireball as accurately as
possible. This requires adequate chemistry codes coupled to the hydro
codes to describe the physics of the disturbed atmosphere in a self
consistent manner. Adequate chemistry codes are generally simpler
versions of more detailed chemistry codes which provide sufficient
accuracy for the purposes of the desired calculations.
The NRL Master Code 1 3 is a detailed time dependent multispecies
code which describes the evolution of ionization and deionization in
the disturbed E and F regions of the ionospere. The calculations of
the ionization and deionization are characterized by two time scales,
the early time and the late time. The early time signifies the photo-
deposition phase and the late time commences with the termination of
the ionizing radiation. During both of these phases a large number of
reactions occur which determine the time histories of the species andNote: Manuscript submitted November 13, 1979.
f1 1-A
temperatures of interest. The most up to date version of this code has
been reported recently4 where the most appropritate and up to date re-
action rates are incorporated.
The details of the photodeposition for the NRL Master Code was
repoted ome ime 2,5reported some time ago. However, in view of current data on photo-
ionization cross sections, a revision of the photodeposition phase of
the NRL Master Code is warranted. This report, therefore, deals with
the details of the photodeposition where a large number of ultraviolet
and extreme ultraviolet spectral lines are considered.
II. PHOIDDEPOSITION
The photodeposition of the NRL Master Code consists of the irradi-
ation of the E and F regions by a large number of uv and euv radiation.
This radiation consists of resonance and other strong uv lines emitted
from oxygen and nitrogen atoms and their multiply ionized ions. A list
of these spectral lines, their excitation energies6 (the energy of the
emitted photon), the species which emit them and their code designations
is given in Table I.
Table I
Spectral Line Excitation Source of Code(A) Energy (eV) Emission Designation
1303.50 9.50 01 L1
1240.10 10.00 NV L2
1199.90 10.33 NI L3
1134.60 10.92 NI L4
1085.10 11.43 NII L5
41 2
Table I
Spectral Line Excitation Source of Code(A) Energy (eV) Emission Designation
1033.80 11.99 VIL
1026.60 12.10 0 L
990.98 12.51 NII I L8
989.50 12.54 01 L9
916.34 13.53 NII L10
878.50 14.11 01 Ll
834.50 14.86 0111 L12
833.80 14.87 Oii L13
811.40 15.28 01 L14
789.36 15.71 ON L15
765.14 16.20 Niv L16
764.01 16.23 NIII L17
703.36 17.63 0111 L18
685.71 18.08 NII I L19
671.48 18.46 NII L20
644.99 19.22 NII L21
629.73 19.69 OV L22
609.35 20.35 O L
554.37 22.36 Oiv L24
539.40 22.99 Oil L25
533.67 23.23 NII L26
529.68 23.41 NII L27
,A r
Table I
Spectral Line Excitation Source of Code(A) Energy (eV) Emission Designation
507.93 24.40 O111 L28
452.11 27.42 NIII L29
430.09 28.82 Oii L30
374.44 33.10 NIII L31
374.12 33.14 0111 L32
305.72 40.5 OIII L33
303.66 40.8 0111 L34
279.83 44.3 OIV L35
247.20 50.2 NIV L36
238.50 52.0 ON L37
209.28 59.2 NV L38
These spectral lines irradiate N2 , 02 and 0 which are the con-
stituents of the ambient E and F regions and are considered to be mainly
in their ground states. However, the irradiation time is generally long
compared with the dissociative recombination times of N2+ and 2*. These
recombinations form additional species e.g., N, N(2D), N(2p), O(1D), 0
(1S), etc., which have to be considered in a detailed photodeposition
scheme.
The uv-fireball is a disturbed ionosphere with dimensions of
hundreds of kilometers whose degree of ionization (or disturbance) at any
point in space depends on the amount of absorbed radiation at that point.
Thus the degree of ionization at any point in the uv-fireball depends
directly on its distance from the radiation source (the fireball). This
4LL 4 4
-r --
in principle requires a time and space dependent attenuation calculation
of each spectral line emitted from the fireball. To illustrate, let I.
(r,t) indicate the flux of a spectral line at time t a distance r
from the fireball which can be considered as a point source. Then
I,(r,t) - 1 IX(ro,t) exp(- 1r Ni(rt) at,(Ni)dr) (1)
4wr2 I ro
where ro defines the coordinates of the fireball, Ni(r,t) is the space
and time dependent density of species, i, and at'X(Ni) is the total
absorption cross section of radiation at wavelength x by species Ni . The
exponential factor in equation (1) determines how far a given wavelength
can be transmitted in any given direction before it is extinguished. The
ion production rate from species Ni, can be given by
dN (r,t)_ = E I (r,t) ai, (Ni) N. (r,t) (2)
where i,, (Ni) is the photoionization cross section of species Ni due to
radiation at wavelength, A. On the other hand, the dissociation rate of
molecular species is given by
dN2 i (rt)dt - -t I,(r,t) ad,A (N2 i) N2 (r,t) (3)
where ad,X (N2i) is the photodissociation cross section of mlecular
species N2i due to radiation at wavelength A.
It is obvious from equation (3) that three quantities at, i and
ad are required for a detailed photodeposition calculation. However, in
addition to these, the final states of the ion, in the case of ionization,
and that of the atom, in the case of dissociation, are very essential.
In the case of ionization, one requires a knowledge of the partial photo-
5
4'l I
-- - ""- II
ionization cross sections at each wavelength, where generally each
species has several ionization continuzn. For example, for a 20 eV
photon (,L620 X) the nitrogen molecule cuould be in any one of its ionic
states of X2E, A2, and B2E whose ionization thresholds are at 15.58,
16.7 and 18.8 eV, respectively. The importance of the partial photo-
ionization cross sections are obvious for several reasons: (1) They
provide accurate photoelectron energies, (2) They provide the produc-
tion rates for the excited states of the ions which are either meta-
stable or radiatively allowed. If the state is metastable it could
react faster with other species and hence affect the chemistry of the
disturbed atmosphere. A good example in this case is the production
of O+(2D) which charge transfers with N2 to produce N2+. The signif-
icance of this reaction is very clear for the disturbed upper atmosphere,
where an atomic ion is converted into a molecular one which generally
recombines with the free electron at a much faster rate. Furthermore,
if the ionic state is a radiatively allowed state it could lose its
energy by radiation, deexcitation by electrons, and by quenching with
neutrals. These, depending on the density regime, provide fluorescence
emission and may raise the kinetic energy of the electron and the
neutral species. At shorter wavelengths dissociative ionization of
the molecular species begin to contribute appreciably to the total
ionization. This should be known accurately since they produce atomic
ions whose recombination rates are not as fast as those of molecular
ions. The final states of the atomic species due to photodissociation
of the molecules provide much necessary information. These are the
6
.* t
i " -
direct heating of the neutrals and the production of the metastable
atomic states. The metastable states provide several interesting line
emissions, contribute indirectly to neutral and electron heating and
produce additional ionization due to photoionization by long wavelength
radiation. Furthermore, atomic metastable states contribute to the
formation of additional species through neutral reactions, e.g., N(2D)
+ 02 NO+ 0).
III. PHOTOABSORPTION AND PHOTOIONIZATION OF N2
The photoabsorption and photoionization cross sections for N2
in the wavelength range of interest have been measured previously (up
to 1965) by many investigators.-12 These measurements and the measure-
ment of others have been reviewed by Hudson13 This review also covers
measurements of photoabsorption cross sections for other atmospheric
molecules. While most of these measurements were concerned with the
total photoionization cross section, some partial photoionization
cross sections were reported by Blake and Carver14 in 1967. However,
recently, total15 and partial1 5'16 photoionization cross sections for
N2 have been reported over a wider range of wavelengths of interest.
The agreement between these recent measurements are reasonably good,
however, the agreement between theml 5 and the older measurement 14 are
poor.
In Table II we present the total photoabsorption, total and
partial photoionization cross sections for the wavelength given in
Table I. The branching ratios for the partial photoionization cross
sections are shown in Figure 1 based on the measurements of Samson,
, , '' 1( 7
et all5 The data for the partial dissociative ionization are from
Wight, et a117 as given in Reference 16. The sources for the data
in Table II are indicated, however, the main source is due to the
recent measurements of Samson, et al.
8
SIf
v- r -4 r-4
0
o c
0
.r4
N
04-)
r--4
4-)4
0 0 0 CD C) 0,n C
0
.,g 0 0 0 0 0 0 N nC ~~ ~ Q 9K i
.- :Y i i L 0 4
\0 CD~ 0 0 0 00 n n n t
CD~~~~~ ~ ~ ~ ~ Rt 0Mm c 0r- -t 4O 0 C4
l< to~ " "4 u4 0 0D 0D CA M~ (M 00 00 00 00 r- r- i. tr-
'+4 00 Ln) Lf) ULtn U) U) U)L n L L n L n I)U)U)U U)fU U)fU ULI)LG0 v4 4 4 v- 4 -4 4~ r-4 r-4 P-,4 r -4 1 -4 - l , I -4 f-4 r-4 r-
0
th0
o c> 000 0) t-- U) LI) m t-) ai )U)L t-) m cOON0)60)*i 4 '-' C 1 c; C
01
0%
%0 N1 tn) M/ M4 ) M' M) MI N ) M D - "Mtqe ) Nr- -4 0 . -4 4 -4 r-4 "4 P-4 v.-4 -4 P4 ,-4
H -4 0 - -N N 00 0) a) 0) 0 ) 0 D 0 -N l V) MI N q N -IrI 0 f-4
4-)
0
0U) L) U) CDal MI N- tN NT qt q UL) U)UnLn))Ln ULI U)On c
J14 , . " ;t L 4, 4C 94;C ;0M "' N 4 N q C4) N N N N 4 P-4 ,-4 r-4 r-4
O- 00 M t LI) L ) 0- c ~ -1C D 4
%6 %o U) LA Ln ) t qr in,-m4m-0in 0m
01
With the data for the partial photoionization cross sections given
in Table II one can claculate the average energy of the ejected photo-
electron for each spectral line. These energies are given in Table III.
Table IIIAverage Photoelectron Energy
From N2 For Each Ionizing Wavelength
PhotoelectronWavelength Designated Flux Energy (eV)
1303.5 L--
1240.1 L2 --
1199.9 L3 --
1134.6 L --
1085.1 L--
1033.8 L6 --
1026.6 L7 --
990.98 L8 --
989.5 L9 --
916.34 LIO --
878.SO --
834.50 L--
833.80 L1--
811.40 L--
789.36 L1 5 --
765.14 LI6 0.62
764.01 L17 0.65
703.36 L18 1.28
685.71 L19 1.73
671.48 L20 2.10
644.99 L21 2.57
629.73 L22 3.06
609.35 L23 3.73
554.37 5.85
539.40 125 6.47
533.67 L26 6.76
4 I 11
I ' i
Table III (Continued)
Average Photoelectron Energy EjectedFrom N2 For Each Ionizing Wavelength
Photoelectron
Wavelength Designated Flux Ejected
529.68 L27 6.94
507.93 L28 7.94
452.11 L29 10.74
430.09 L30 12.09
374.44 L31 16.10
374.12 L32 16.12
305.72 L33 22.20
303.66 L34 22.52
279.83 L35 22.55
247.20 L36 32.92
238.50 L37 34.8
209.28 L38 39.42
However, one can simplify the calculations by regrouping of the
spectral lines in a manner similar ° to the solar ionization of the
ionosphere. The regrouping depends on the degree of accuracy desired
in the calculation and will be discussed later in this report.
V, 12
r I
IV. PHOTODISSOCIATION OF N2
In Section II data were presented for the total photoabsorption
cross section in N The total and partial photoionization cross
sections were also given including the relevent cross sections for the
dissociative ionization. In this section a discussion is given on the
photodissociation of N There are several photodissociation limits 21
for N2 where the products of the dissociation leave the nitrogen atoms
in excited states. These dissociation limits, their threshold energies
and the states of the dissociation products are given in Table IV, re-
produced from Reference 21.
TABLE IV
Photodissociation Limits Of N2
Limit Products Dissociation Wavelength (1)
________ Energy (eV) _______
D S + S 9.76 1270
4D 2 D + S 12.14 1021
2 4D P + S 13.33 930
2 2D D + D 14.52 853
2 2
D52P4+ D 15.71 789
D p + P 16.91 733
4 4D P + S 20.08 6177
13
L I
The photodissociation limits presented in Table IV produce
states which are basically metastable, i.e. 2D and 2P and a radi-
atively allowed excited state 4P which emits ultraviolet photons
( - 10.3 eV ). These metastable states canin principle, be photo-
ionized by radiation of longer wavelengths compared to ionization
from the ground state of the species.
There exist reliable measured photoabsorption and photo-
ionization cross sections for N2 ( see Section II for references).
However, the same cannot be said for photodissociation of N2 . In
fact one may observe that no data is available for the simple photo-
dissociation of N2 . However, some estimates can be made 21 from
a knowledge of the measured total photoabsorption and photoionization
cross sections. In Table V we present such an estimate based on the
work of Reference 21, however, modified to conform with the average
total absorption cross sections given in Table II. We also present
in this table the products of the dissociation and the excess energy
which goes into the kinetic energy of the neutrals.
14
Table V
N2 Dissociation Cross Section (Mb)
The Dissociation Products and the Excess EnergyGoing into the Kinetic Energy of the Neutrals
q b)Exces . ry
D ) Products E e e
4SL9 989.50 0.08 S +1) 0.42
L 916 0.14 S + 2 D 1.41
L 878.5 0.30 4S + 2P 0.78
L 834.5 1.4 4 S + 2P 1.5312
L13 833.8 1.5 S + 2 1.54
L " 11.4 1.2 4 S + 2 1.95
L15 789 2.2 2 P + 2D 0.0
L16 765 1.8 2 + 2D o.49
L17 764 1.8 2p + 2D 0.52
L18 703 o.8 2p + 2D 1.92
15
V. PHOTOIONIZATION OF N
The phototonization cross section for the ground state of the
nitrogen atom has been calculated by many workers using various theo-
retical methods 22" . Henry's results 23 agree reasonably well near
threshold with experimental measurements of Comes and Elzer 7. Rea-
sonable agreement also prevails between the calculations of references
23, 24 and 26.
Of more interest, however, is the photoionization cross section
of the ground state configuration of N i.e. N (4S), N (2D) and
N (2). Such data has been presented by Henry2e in a functional
form fitted to the calculated value. The functional form is
aX= C r ,X 6 1 01 c2(4L 1 ~ )S + (l (m2) (4) S~
where Xo is the threshold wavelength for the transition and a, S and
Oth are parameters whose values are given in Table VI.
16
Table VI
Photolonization Cross Section Parameters for N
Transition S th
N( 4S)-.+ (3P) 2.0 4.287 11.42
N(2D)-.N (3P) 1.5 3.847 4.41
N(2D)-.N (-D) 2.0 4.826 5.02
N(2P)-.N ( P) 1.5 4.337 4.2o
N(2P)- (1D) 2.0 5.112 2.87
N(2P)--N ( S) 2.0 4.727 2.03
Using the parameters given in Table VI and equation (4),
the photoionization cross sections for the ground state configu-
ration of N are presented' in Figure 2 as a function of wavelength.
Using this figure, the ionization cross sections for N(4 S), N(2D)
and N(2P) are presented in Tables VII (a) and VII (b) for the Set
of ionizing radiation of Table I.
' 17
,*'[ I
Sd I@ LC\ 61N Url v U '
0
p N\ N O\ 4 U'\41. .. .
(S o cu I S S
4 ~0 K' IS 0 \10 m) 0\ 0 0 0 0 O
> -4
UU
00S3 FL.-
-ca
t- fr- t- K~- . .0 '0 - O'\0 ~ ~ ~~r 0r \ L' ~ . ~ -
0 rS.'r r\ U\ L\ N V :
O L-t ir M CM. cc) cmC- C 4 - - 4 - 4
*: *) (s 0 0 .- Cu U, .
0x 0 _t \ \ \0 -4 - -4 -4 -4 -4 44)A )
C
040
Q PQ
A -14 -o 124r OC) KD - Co o C. 0 4) r\ C
'U t- C j r4 0 -4 u \ - P - O N0 .4 .4 N4 Cu u u C C ; C ; Cu c Cu N
44
0
4'
419
K
oO "O0 'o t- u
0 0 4 OD um -t 0a . .0$4
aa
P4 -: co -t -r( C
pq < ~ m* M. K\\ r C
a 0
4
4
0 X .u41
0ca
$4 r. 5
02
0 0
t-- 0 (7\CU 11:-
> 0 0 -
CU CU CU
1014
41 )$4-
0 44
H 0 Ca C c~-
4 $
K) _t L\ CO t,- U,- 0 N4 CU \ -:t*
1-0
0 U\ t- t oao 0 4 0 \ Or\
0
0
-44 50
0o 1.0 4.)04 C 0 -4 CUj hl -z Lr'. \0
T JN 4'-r 4 4 -
4 21
t- \ -4 O -:t ur\ 0
.4 CM K-\ W\ _t --t V% tl- I- co co
cu K N\ N CU cu CN -4 (ON ON CY\
0 o CU CU CU CU CU CU CU -4 -54
48
V
-4
C: ~ ~ -4 K L\ N UN K\D '\ t-j ONl N .41 C 40 0 ON 'D N U4U
41 w
0 4 4
o 41
-~0.0 U
0 Cd1. 4 Js-4 CO
En 9 9N"\ t- LC,\04 t- t- CU _zt o\N- C-~
* . . -4 CU CU4 CU4E 1-4O- 0 fN"I ' lON CO ORa L~ -Z CU ON CO CO C-u-~ - _:f --t _:t _:t K\ \ hN% N
S0
0
'.4
0
-1 4
-4 -r4 1 Cl .cl ,
o r22
pa .4-4 (T\ ON N 0\ 0\ ON CY\ CON m
C~f l C'J C * CC L C
04 - 4 4 0 0 0 0 0 0
4j
0-4 c : , , : - 4 -t -t -t -
V 0 ON \.OJ-4 - 4 4 0
00
U 44
0 : z0 ' - L
U- 41 0o
.0 U.o
E-4 0 0C 1 4 M ~ I : :
0 ~ ~ ~ " CCI CC \01 -4\ -4 -4- t- '-4\1 D
0
0
N
0
0 ow
0 10
(0 0 00 4 \ N - r \D t- O,4 4.10 0 0
23
VI. Photoionization of 0
A recent measurement3° of the photoionization cross section of
atomic oxygen in the wavelength region of 900 - 760 A gives results
in close agreements with the measured values of Cairns and Sampson3 l .
More rigorous and recent theortical calculations2 4'28 '3 4 predict
results in reasonable accord with these measurements. However, early
theortical calculations3 4 '3 5 have predicted results, near ionization
threshold, which are lower by a factor of 2.
For a detailed photodeposition, one requires photoionization
data for the ground state configuration for which no experimental
data is available. However, theoretical calculations2 8 '3 4 exist and
we shall utilize the results of Henry2 8 by multiplying them by a factor
of 1.6 to bring them into accord with the experimental data, espec-
ially for the transition 3P _ 4S. Figure 3 presents the photoionizadm
cross sections of O(3P), 0(1 D) and 0(1S) calculated using equation (4)
whose parameters relevent28 to oxygen are given in Table VIII.
24I. , g t
E r
Table VIII
Photoionization Cross Section Parameters for 0
Transition S th
4
(3P).o (4s) 1.0 2.661 2.94
O(3 p)-.O+ (2 D) 1.5 4.378 3.85
0(3p).o 2P) 1.5 4.311 2.26
1 +
( D)- p) 1.5 4.8 1.95
0( S)--O ( 2 p) 1.5 5.124 7.65
Tables IX a andIX b present the relevent photoionization
cross section for the set of ionizing radiation of Table I. The
energy of the ejected electrons are also given in Tables IX a and
IX b.
25
0 -
$.4 Cu u C41
zict - L~ u ~-ge '' .0 C Cu i \l K'
4
0 4"4.
44
1-4 U
4.4'
44 H C r~- L \ \.D t CO r-O \ 0 -4 Cu C
C: w 0 ~. -4 -4 '-4 Cu Cui Cuj Cutt -- r
414
8 4
>N -H- t- £U-
so V * 06 0 ;4 ;* H Cul Lr'0\ all --- L\~ -1 -, 4 C u C
0 11 r.- Ll t1 - '. C CU OR C) 11-
1
u
4 ~ ~ ~ O ON o- 0 t-- --t r4 Cq'- D
0 44 C~
0 40 c!~'0 '0 . ' -4 -C u C
4J0 0\ 40 w4 U, 0 O -- c :3:t L\ c
00
4
_-t \1 ta) * *0 0 Lrj ON 0
-~ ON ON ON -4 - .4 .4 '-
-,4
S2
4)
-4 1.4 -
4)
44 O0 0 O
14
00
0 10
04)',, c'
E-4 0J
0 U
'
0
0
"4
01of
ol -o
-41
28
N _t t \0 ON ON 0 0 0
-4 -4 -4 -4 -
-4
41 0
01
taN -v 1. U'\ 0 '
01 -. -1 ('1N
410i K 6 _ -4 (J (N PC\ _:t (NJ (t
1.4
~V
od C) 0 -4 -4 (NJ -4 Au- "4 . "4 0 ND 1.4 C- Pr P~ Ac'- &IC
02
pa C%) Lr t-- 00O - 4 4 C
c: O 1 1 - u- L Ul m- ~ f
0
-4K\ C\- wco a %o
00
4
0 1
.0 0 4" 0 i- ~
rf\ Cuj Cu R
0* v4. -~ - - -S
4.4 a) K"O 0 t:t:
0
a, 4
0 m) t(
0
0 441
03
UU
.0
'4
-0
40 C.II,
0)
0 41C
80
0
14004
0 t0
31
VII. Photoabsorption and Photoionization of 02
The absorption cross sections for molecular oxygen have been
measured below 1300 1 by many workers" 19''
35and the data have been
reviewed by Hudson13 . Above 1300 1 the absorption cross section have
been measured by Watanabe, et al,3 7 and Metzger and Cook.3 8 Partial
photoionization cross sections are available,14'" however, over a
limited range of wavelength. Dissociative photoionization cross
sections have also been measured 4° , again, over a limited range. Using
these data, the total photoabsorption, photoionization and partial
photoionization cross section are presented in Table X where the source
of the data is also indicated. For regions of wavelength where no
measurement is available estimates are provided. The photoionization
to different continuum states of 02 e.g. X2,t, b E and dis-
sociative ionization are considered.
*32p., ,/
O\Lr LI t\ U\N tC\ U'\ LI\ L(\ 0 r 6'\ U\ Ur\
aa
0
0
.0O1 .-
0
'. .-.
co r4 0 C~ c
0
,4
0
410 P4r.4~ .
cJ J
UIU"U4- - : , I\W 01 \e UA.. CY i 8'0-O\ (4N c 0'
.c) t - t - t
4~( -U -4~ 04 4
'.4 a a a a a a a a a a a
LrN um~ u\ u-\ u-\ ur Lr,\ u-' 0 L,- 0 0 (3 C; C; ..3 -4C;KKNt \ C' N~ K 4 Nr -i -4 P4 -4 -4-r4 4 .
0t a\1 0 4 -0 * -4 _z-4 t -4 0 0 0 0 0 0 0 0
-4
0~ ~ u Ol\ a)'~ 0- 4 M 4r 00 0 0L- -4 0 0 0
*0* 41
00 bC KNK IM c
-A
U . bJ' 1 UN tl- I'D Lv' Lt'\ uL\ LU- KN -N K% N'~ C j C -4 -4
w
-4
- 4 , , iL\ K l 1 r r l r\ CQ CU Cu CU CUJ CU
10
C; CUj-2 CUj L1 \.o \o t-t- -.1ooc 0 0 -* z a 00 0o .
CM"-4 NCMCU 0CM~ OO- UiO
0I
0 b 2 A f * \ p \F - -t AC 0\ t - c) C 0D 0 O -fl 0 \ 0 0 ,
CU\ CU CUJ CUM 4 4 4 4 4-
A4
r4
0
'0 UN r\L Ul\ ** - N pC rN 01%c
34
The average energy of the ejected photoelectron can be calcu-
lated for each ionizing wavelength knowing the ionization threshold
and the photoionization cross section. However, in 02 the photo-
ionization continuum lead to four discrete ionic states in addition
44to the dissociative ionization. These states are X2-T, a 4 T, A 2 T and
b 4Z whose ionization thresholds are 12.06, 16.1, 16.8 and 18.2 eV
respectively. The A 2i and b 4 states are coupled radiatively to
X 2n and a 4iT states, where the X2 state is the ground state of the4.
molecular ion and a 4r is an excited and a metastable state. Thus,
for the purposes of ionization one can consider the molecular ions
to be in X 2 and a 4i states only and calculate the average photo-
electron energy by utilizing the detailed data of Table XI.
Table Xl
Effective Photoionization Cross Section of 02 (Mb)
And the Average Energy of the Ejected Electron
For Each Ionizing Wavelength
Wavelength Designated Flux q(X) a(a) a(di) AE*(eV)
1303.5 L 1 -.......
1240.1 L L 2 ......
1199 .9 L ........
1n34 .6 L4 ........
lO85 .1 L ........
1033.8 L6 ........
1026.6 L7 0.90 0.0 -- 0.04
990.98 L 2.1 0.0 -- 0.45
I
Table XI Continued
Effective Photoionization Cross Section of 02
And the Average Energy of the Ejected ElectronFor Each Ionizing Wavelength
Wavelength Designated a(X) a(a) a(di) AE (eV)_ lux
989.5 L9 1.0 0.0 -- o.48
916.34 LO 2.7 0.0 -- 1.47
878.50 L 11 3.7 0.0 -- 2.05
834.50 L12 4.4 0.0 -- 2.8
833.80 L 3.7 0.0 -- 2.81
811.4o L14 14.8 0.0 -- 3.22
789.36 L15 11.1 0.0 -- 3.65
765.14 L16 11.2 1.2 -- 4.14 - 0.1764.01 L17 10.2 1.1 -- 4.17 - 0.13
703.36 L18 15.5 6.7 -- 4.65 - 1.53
685.71 L 12.8 9.5 -- 4.24 - 1.98
671.48 L20 7.5 14.7 -- 4.44 - 1.14
644.99 L2 1 7.6 15.2 0.3 5.29 - 1.75 - 0.51
629.73 L22 10.3 20.1 0.8 6.02 - 3.63 - 0.98
609.35 L23 9.7 14.5 1.3 6.87 - 3.03 - 1.64
554.37 L24 10.0 11.6 4.0 8.12 - 5.10 - 3.65
539.40 L25 9.8 11.5 4.3 8.70 - 5.72 - 4.28
533.67 L26 7.3 12.1 4.3 8.57 - 5.89 - 4.52529.68 L27 7.3 12.1 4.3 8.75 - 6.07 - 4.7
507.93 L28 7.3 11.1 4.o 9.74 - 6.95 - 5.69
452.11 L29 7.7 11.1 2.0 12.58 - 10.07 - 8.71
36
# . *
I I . n .
Table XI Continued
Effective Photoionization Cross Section of 02
And the Average Energy of the Ejected ElectronFor Each Ionizing Wavelength
Wavelength Designated a(X) a(a) a(di) AE(eV)Flux
430.09 L30 7.7 9.7 1.0 13.40 - 11.38 - 10.11
374.44 L 31 7.7 0.1 0.5 17.51 - 15.75 - 14.39
374.12 L32 7.7 10.1 0.5 17.51 - 15.75 - 14.43
305.72 L33 6.9 9.0 0.5 25.69 - 23.00 - 21.79
303.66 L34 7.1 9.0 0.5 25.93 - 23.3 - 22.09
279.83 L35 6." 8.2 0.5 29.67 - 26.66 - 25.59
247.20 L36 5.3 6.2 0.5 35.8 - 32.74 - 31.49
238.50 L37 4.7 5.8 0.5 37.92 - 34.45 - 33.29
209.28 L38 4.7 5.8 0.0 45.1 - 41.65 - 40.49
In this Table the energy of the ejected electron is given in three
columns to correspond from left to the ionization limits a(X), a(a)
and a (di), respectively.
VIII. PHOTODISSOCIATION OF 02
The oxygen molecule has many photodissociation limits where the
products of the dissociation are oxygen atoms in excited states. The
lowest dissociation limit is at 5.1 eV and the dissociation products
are two atoms which are in the ground state. However, since we are
interested in the photoabsorption at and below 1303 1 the dibbociation
limits of interest begin with the product of O(3p) + O(Is). Table XII
presents the dissociation limits of interest, their threshold energy
and the products of the dissociations.
• p" 37°I.
E - -_. . . .. .
Table XII
02 Dissociation Limits and Dissociation Products
Energy Threshold (eV) Wavelength ( ) Dissociation Products
9.31 1331 3P + I s
11.27 1100 ID + S
13.51 918 s + s
3 514.20 869 3P + S
14.64 847 3P + S
15.86 782 3P + 5p
16.1o 770 3p + 3p
16.55 749 1D + S
16.95 731 3p + 5S
17.05 727 3P + 3s
17.19 721 3P + 5D
17.20 721 3P + 3D
The dissociation cross section for 02 from 1303 to 918 A are
taken from Tables XI (a,b) where we consider the total absorption to
lead to dissociation in the absence of ionization. From ionization
threshold to 918 1 we take the difference between total absorption
and ionization to lead to dissociation. For wavelengths below 918
we utilize the measured values of Matsunaga and Watanabe3 5 down to a
38
wavelength where the ionization efficiency becomes 100%. Using these
data, the dissociation cross sections of 02 and the states of the
dissociation products along with the excess energy which goes into
the kinetic energy of the neutral particles are presented in Table XIII.
Table XIII
0 Dissociation Cross Section (Mb), the2
Dissociation Products and the Excess Energy
Going into the Kinetic Energy of the Neutrals
Designated .d Products Excess Energy (eV)Flux
L 0.5 3p + 1S 0.19
L 0.2 3p + 1S 0.69
L3 1.6 p + s 1.02
L4 1.0 3p + 1S 1.61
L 1.0 D + S 0.16
L6 0.9 D + 1 S 0.72
L7 0.5 D + S 0.83
L8 1.2 D + lS 1.24
L9 0.5 D + S 1.27
L 0.5 S + S 0.02
L 2.3 s + S o.6
39
Table XIII Continued
02 Dissociation Cross Section (Mb), the
Dissociation Products and the Excess Energy
Going into the Kinetic Energy of the Neutrals
Designated ad Products Excess Energy (eV)
Flux
L12 5.5 3 P + 3 S*(3p)(*) o.2
L13 5.5 3P + 3S*(3p) 0.23
10.2 + 3S*(3p) 0.64
L15 9.2 3P + 3S*(3P) 1.07
L16 8.1 3P + 5p(p) 0.1
L 7 8.1 3p + 3p*(3p) 0.13
L18 2.7 3P + 3 S*(3P) 0.58
(*) The state in the bracket is the final state since the original
product is radiative and cascades to the ground state after emitting
it excitation energy.
4oV..#
References
1. A. W. Ali, "Electron Pressure Profile in the F-Layer UV-Fireball",
Plasma Dynamics Tech., Note 20, Plasma Physics Division, NRL(1969)
2. A. W. Ali, "The Chemistry and the Rate Coefficients of the F-Layer
UV-Fireball", Plasma Dynamics Tech. Note 24 (1970).
3. A. W. Ali, "The Physics and Chemistry of Two NRL Codes for the
Disturbed E and F Regions", NRL Report No. 7578(1973).
4. A. W. Ali, "The Physics and the Chemistry of NRL Master Code for
The Disturbed E and F Regions", NRL Memorandum Report No.3732(1978).
5. A. W. Ali and E. B. Hyman, "Summary of NRL Results for First
Chemistry Benchmark Meeting", RAND Corp., BO-31 March 1971(May 1971).
6. W. L. Wiese, M. W. Smith and B. M. Glennon, "Atomic Transition
Probabilities", NSRDS-NBS 4, Vol. 1. (1966)
7. See for example, F. R. Gilmore "Potential Energy Curves for N2 , NO,
02 and Corresponding Ions", RAND Corp. Memorandum RM-4034-1-PR (1966).
8. R. E. Huffmian, Y.Tanaka and J. C. Larrabee, J. Chem. Phys. 39, 910
(1963).
9. G. R. Cook and P. H. Metzger, J. Chem. Phys. 41, 321 (1964).
10. J. A. R. Samson and R. B. Cairns, J. Geophys. Res. 69, 4583 (1964).
11. J. A. R. Samson and R. B. Cairns, J. Opt. Soc. Amer. 55, 1035 (1965).
12. K. Watanabe and F. F. Marmo, J. Chem. Phys. 25, 965 (1956).
13. R. D. Hudson, Rev. Geophys. Space Phys. 9, 305 (1971) and refer-
references therein.
14. A. J. Blake and J. H. Carver, J. Chem. Phys. 47, 1038 (1967).
. r' ,41
, l
15. J. A. R. Samson, G. N. Haddad and J. L. Gardner, J. Phys. B: Atom
Mol. Phys., 10, 1749 (1977).
16. E. W. Plummer, T. Gustafsson, W. Gudat and D. E. Eastman, Phys.
Rev. A. 15, 2339 (1977).
17. G. R. Wight, M. J. Van der Wiel and C. E. Brion, J. Phys. B: Atom
Mol. Phys. 9, 675 (1976).
18. G. V. Marr, "Photoionization Processes in Gases", Academic Press,
New York (1967).
19. K. Watanabe, Adv. Geophys. 2, 153 (1958).
20. A. W. All and P. C. Kepple, "Solar Ionization Rates For The
Ionosphere E, F and D Regions", NRL Report 7598 (1973).
21. G. R. Cook, M. Ogawa and R. W. Carlson, J. Geophys. Res. 78,
1663 (1973).
22. R. J. W. Henry and L. Lipsky, Phys. Rev. j15, 51 (1967)
23. R. J. W. Henry, J. Chem. Phys. 48, 3635 (1968).
24. G. M. Thomas and T. M. Helliwell, JQSRT, 10, 423 (1970).
25. A. Dalgarno, R. J. W. Henry and A. L. Stewart, Planet Space
Sci., 12, 235 (1964)
26 S. Ormonde and M. J. Conneely, Q-SI-TR-70-69, Dec. (1970).
27. F. J. Comes and A. Elzer, Phys. Letters 25A. 334 (1967).
28. R. J. W. Henry, Astrophy. J. 161, 1153 (1970).
29. A. W. Ali, "Photoionization Cross Sections of 0 and N Atoms
and Their Low Lying Metastable States", NRL, Plasma Dynamics
Technical Note 32 (1971).
42
V., f
30. J. L. Kohl, G. P. Lafyatia, H. P. Palenius and W. H. Parkinson,
Phys. Rev. A 18, 571 (1978).
31. R. B. Cairns and J. A. R. Sampson, Phys. Rev. D2 A 1403 (1965).
32. K. T. Taylor and P. G. Burke, J. Phys. B 2. L 353 (1976).
33. A. K. Pradhan and H. E. Saraph, J. Phys. B 10, 3365 (1977).
34. A. Dalgarno, R. J. W1. Henry and A. I. Stewart, Planet Space Sci.,
12, 235 (1964).
35. F. M. Matsuraga and K. Watanabe, Sci. Light. 16, 31 (1967).
36. R. E. Huffman, J. C. Larrabe and Y. Tanaka, 3. Chem. Phys. 40,
356 (1964).
37. K. E. Watanabe, E. C. Y Inn and M. Zelikoff, 3. Chem. Phys. 21,
1026 (1953).
38. P. H. Metzger, and G. R. Cook, JQRST, 4, 107 (1964).
39. A. 3. Blake and 3. H. Carver, Phys. Lett. 12, 387 (1965).
40. F. 3. Comes, F. Speier and A. Elzer, Z.Natureforsch, QA, 125,
1968.
43
100
80-
0 6
0
z
z< 40
20-
0.750 650 550 0 450 350
WAVELENGTH (A)Fig. 1 -Branching ratio of various photolonimation continue of N2
as a function of the wavelength of the incident radiation
44
12.0-
11.0 4S*-N3p
10.0-
9.0-
8.0
~70
S6.0
5.0-
4.0-
NC2 D) W.MN(3P)
3.0
2.0-
1400 1200 1000 800 600 400 200 0
Fig. 2 -Photoionization cross sections for the ground stateconfigurations of nitrogen atom
V., j445
11.0
10.0-
9.0-
70-
o6.0-
0 0(3 p) -a-0 2D0
4.0-
3.0
Q( 3p)~ Ot(2 p)2.0-
I0-0( D) -0- 0 (2 2p)
1000 800 600 400 200 0
Fig. 3 - Photoionization cross section for the ground stateconfigurations of the oxygen atom
46
TV *
