Solar Photo Rates for Planetary Atmospheres and Atmospheric Pollutants

298 Pages·1992·11.448 MB·English

by  W. F. Huebner, J. J. Keady, S. P. Lyon (auth.), W. F. Huebner, J. J. Keady, S. P. Lyon (eds.)

SOLAR PHOTO RATES FOR PLANETARY
ATMOSPHERES AND ATMOSPHERIC POLLUTANTS
SOLAR PHOTO RATES
FOR PLANETARY ATMOSPHERES AND
ATMOSPHERIC POLLUTANTS
Edited by
W. F. HUEBNER
Southwest Research !llStitute, Sail AlltOllio, Texas, U.S.A.
Los Alamos Natiollal LaboratOlY. Los Alamos. New Mexico. U.S.A.
J. J. KEADY and S. P. LYON
Los Alamos National Laboratory. Los Alamos. New Mexico. U.S.A.
Reprinted from Astrophysics and Space Science
Volume 195, No. 1, 1992
SPRlNGER-SCIENCE+BUSINESS MEDIA, B.Y.
Library of Congress Cataloging-in-Publication Data
Solar photo rates for planetary atmospheres and atmospheric pollutants
! edited by W.F. Huebner and J.J. Keady and S.P. Lyon.
p. cm.
ISBN 978-90-481-4212-5 ISBN 978-94-017-3023-5 (eBook)
DOI 10.1007/978-94-017-3023-5
1. Molecular astrophyslcs--Observatlons. 2. Solar radlatlon
-Observatlons. 3. Atmospherlc chemlstry--Observatlons.
4. Photodlssoclatlon--Observatlons. I. Huebner, W. F. (Walter F.I,
II. Keady, J. J. III. Lyon. S. P.
QB462.6.S65 1992
523.01·96--dc20 92-30457
Printed on acid-free paper
AII Rights Reserved
© 1992 Springer Science+Business Media Dordrecht
Originally published by Kluwer Academic Publishers in 1992
No part of the material protected by this copyright notice may be reproduced or
utilized in any form or by any means, electronic or mechanical,
inc1uding photocopying, recording Of by any informat ion storage and
retrieval system, without written permission from the copyright owner.
SOLAR PHOTO RATES FOR PLANETARY ATMOSPHERES
AND AT MOSPHERIC POLLUTANTS
Edited by
W. F. HUEBNER, 1. J. KEADY, and S. P. LYON
T ABLE OF CONTENTS
Introduction
Solar Flux 5
Photo Rate Coefficients and Excess Energies 7
Summary 269
References 289
Index of Species - Full Names 291
Index of Species - Chemical Structures 293
SOLAR PHOTO RATES FOR PLANETARY ATMOSPHERES AND
ATMOSPHERIC POLLUTANTS
W. F. HUEBNER
Southwest Research Institute, San Antonio, Texas, U.S.A.
and
Los Alamos National Laboratory, Los Alamos, NM, U.S.A.
and
1. 1. KEADY and S. P. LYON
Los Alamos National Laboratory. Los Alamos, NM, U.S.A.
(Received 8 April, 1991)
Abstract. Unattenuated solar photo rate coefficients and excess energies for dissociation, ionization, and
dissociative ionization are presented for atomic and molecular species that have been identified or are
suspected to exist in the atmospheres of planets, satellites (moons), comets, or as pollutants in the Earth
atmosphere. The branching ratios and cross sections with resonances have been tabulated to the greatest
detail possible and the rate coefficients and excess energies have been calculated from them on a grid of
small wavelength bins for the quiet and the active Sun at 1 AU heliocentric distance.
1. Introduction
Photo rate coefficients for atomic and molecular species that have been identified or are
suspected to exist in the atmospheres of planets, satellites (moons), and comets, or as
pollutants in the Earth atmosphere are needed for analysis and modeling. Lifetimes
(reciprocals of rate coefficients) for possible mother molecules of observed radicals in
comets were determined by Potter and del Duca (1964) and by Jackson (1976a, b).
Some rate coefficients for several atomic and simple molecular constituents oflunar and
planetary atmospheres have been calculated by Siscoe and Mukherjee (1972), McElroy
and Hunten (1970), McElroy and McConnell (1971), and McElroy et al. (1976), for 10
by Kumar (1982), for Earth thermospheric constituents by Banks and Kockarts (1973)
and Torr et al. (1979), and for solar wind physics by Axford (1972). In addition, lifetimes
for some isolated species or rate coefficients in very limited wavelength bands - e.g., the
solar hydrogen Lo: line - have been obtained by various investigators for special
situations and applications. The compilation presented by Whipple and Huebner
(1976), showed little overlap of calculated and observed lifetimes of molecules in the
solar radiation field. The calculation of rate coefficients for 26 atomic and molecular
species made by Huebner and Carpenter (1979) increased the overlap somewhat. Their
work has been extended here to over 80 species.
If the chief concern is the prediction of potential mother molecules of observed
radicals, then only the main decay branch needs to be considered. For molecules the
main branch is almost always a dissociation, very seldom ionization, and never photo-
Astrophysics and Space Science 195: 1-294, 1992.
© 1992 Kluwer Academic Publishers.
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2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4
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ux 01E 20E 44E80E08E45E09E12E23E42E20E22E77E60E 96E 40E25E2lE32E50E73E88E02E97E13E37E12E 25E16E 19E 38E 70E
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a 68024680257924792581360369360471
W 99000001111122223334445555667778
11222222222222222222222222222222
+ 09 + 09 + 09 + 09 + 09 10 + + 10 + 10 + 10 + 10 + 10 + 10 + 10 10 + + 10 + 11 + 11 + 11 + 11 + 11 + 11 + 11 + 11 11 + +11 + 11 + 11 + 11 + 11 + 11 + 11 + 12
s (A) Flux 3.09E2.57E 2.74E 3.IOE 7.60E 1.0lE 1.30E 1.82E 2.33E 2.66E 2.90E3.60E4.75E 6.40E 5.49E 1.19E 1.76E 2.32E 1.44E 1.83E2.34E 2.62E 2.88E3.14E3.81E4.43E4.95E 5.94E6.59E7.26E9.85E1.27E
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by wavel Wavelen 1351 1360 1370 1379 1389 1408 1428 1449 1470 1492 1515 1538 1562 1587 1613 1639 1667 1695 1724 1739 1754 1770 1786 1802 1818 1835 1852 1869 1887 1905 1923 1942
d
e
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LE I bin -brac1) Flux 1.31E+08 1.31E+08 1.31E+08 6.21E+08 1.31E+08 1.31E+ 08 9.15E+07 7.84E+07 1.03E+ 08 2.66E+ 08 1.12E+ 08 1.24E+ 08 1.82E + 08 1.90E + 08 7.40E+ 08 3.02E+ 11 3.67E+ 09 1.36E+ 09 1.61E + 09 1.32E + 09 1.41E+09 3.1lE+09 1.06E+ 09 1.37E+ 09 1.02E+ 09 1.14E+ 09 7.29E+09 2.20E+09 1.59E+ 09 2.21E + 09 1.24E+ 10 1.99E + 09
B 1
TA 2 S - gth
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photo Flux 2.42E3.62E5.17E 1.02E5.52E1.20E1.15E3.39E 1.59E 5.19E1.28E8.07E2.05E 2.73E3.34E9.39E2.34E5.84E5.94E1.04E1.04E5.30E7.56E1.25E1.04E3.60E2.46E1.83E 1.57E 1.70E1.31E 7.21E
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Wa 525456586062636871747780838689919293949596979899100101102103104105107108
Flux 1.00E-Ol 01 3.00E+ 2.50E+ 03 2.80E + 04 1.80E + 05 4.00E+06 4.70E+07 8.30E+ 07 1.03E + 08 9.40E+07 1.20E + 08 9.90E + 07 5.60E + 07 2.50E+07 1.20E+ 07 3.07E+08 9.00E + 08 3.70E + 09 1.40E + 09 2.65E + 09 4.50E +08 1.54E + 09 +09 5.84E 1.16E +09 4.50E + 08 1.31E +09 I.77E + 08 2.76E + 08 I.77E + 08 2.12E + 08 4.32E + 08 6.32E+ 08
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ux 83E07E 50E96E 51E09E 74E40E18E87E 70E47E31E14E01E87E71E60E48E 41E33E25E16E06E67E25E 84E74E35E22E 59E 53E
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Flux 4.01E 3.89E3.88E 3.78E3.76E3.72E 3.72E 3.79E 3.79E7.49E 2.11El.68E 1.60E 1.50E 1.48E 1.43E 1.32E 1.25E J.l6E 1.12E 1.07E 9.95E 9.72E 9.20E8.24E 7.70E6.94E 6.51E 6.19E 7.46E 1.11E8.28E7.33E
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ed) Flux 2.46E3.90E3.99E3.86E5.08E5.92E6.05E 6.94E 8.12E9.71E8.97E 9.44E1.01E 1.03E 1.03E 1.04E 1.18E 1.23E 1.24E 1.17E1.11E1.09E 1.19E 1.54E 1.90E 1.99E 1.99E 2.02E2.01E 1.94E 1.98E 2.25E2.39E
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Table I Wavele 2857 2899 2941 2985 3030 3077 3125 3175 3225 3275 3325 3375 3425 3475 3525 3575 3625 3675 3725 3775 3825 3875 3925 3975 4025 4075 4125 4175 4225 4275 4325 4375 4425
4 w. F. HUEBNER ET AL.
dissociative ionization. This is immediately apparent from the magnitude of the thresh
old wavelengths for these processes (see Table I) - although a small photodissociation
and a large ionization cross section near the respective thresholds can invalidate such
an oversimplified prediction. Predissociation and autoionization significantly increase
rate coefficients (decrease lifetimes) and, if known, are included in the evaluations
presented here.
Dissociation rate coefficients presented in the literature are often based only on broad
averages over bandwidths of 100 A or more, and at wavelengths not below that of the
hydrogen La line (1215.7 A). Details about branching ratios are usually also ignored.
For terrestrial atmospheric constituents, cross sections have been compiled by Huffman
(1971) and rate coefficients by Baurer and Bortner (1978). Preferred cross sections,
branching ratios, and threshold wavelengths for neutral species occurring in middle
atmosphere chemistry have been evaluated by the CODATA Task Group on Chemical
Kinetics (Baulch et al., 1980, 1982, 1984), while NASA has evaluated and compiled
preferred cross sections for use in stratospheric modeling (DeMore et al., 1982). When
ever possible, we have gone to the original references for these data and supplemented
them with additional data when available. For the extreme UV and X-ray region we have
supplemented the cross sections for molecules from the sum of the cross sections of the
atomic constituents. Cross sections with resonances have been tabulated to the greatest
detail possible and rate coefficients are calculated for small wavelength bins. Most of
the known branching ratios are taken into account as a function of wavelength, but
where necessary, some values have been estimated. In addition cross sections are
estimated for some metastable states.
In Section 2 the solar spectrum is presented for the nonflaring Sun at medium activity.
Also the ratio of the irradiances for the Sun near solar maximum to that of the nonflaring
Sun at medium activity as presented by Lean (1987) based on the Atmospheric
Explorer E (AE-E) data of Hinteregger et al. (1981) is shown, prorated to the wave
length grid used here. In the following we will refer to these simply as the quiet and the
active Sun. Section 3 presents the computed rate coefficients for each photo process
together with the sources for the cross sections, the thresholds, the branching ratios, and
the excess energies. For easy reference the rate coefficients for each process and the sum
for all the processes operating on a mother species are presented in Table II in Section 4.
Also presented in this Table are a quality rating of the cross section data and the mean
excess energies of the solar photolysis products. These energies are relevant for the
heating of an atmosphere or the escape from it. The mother species are listed in order
of the number of atoms in the species: monatomic, diatomic, etc. In each of these groups,
species are listed in increasing order with total atomic number. Species without state
designation refer to the ground state. Since cross sections are measured typically at
temperatures around 300 K, rotationally excited levels in the ground state of molecules
will in effect lower the photo threshold compared to that at 0 K. The molecular rate
coefficients presented here include the contribution caused by the shift to this effective
threshold. Larger contributions from excited states occur at higher temperatures. The
theoretical cross sections correspond to 0 K.
SOLAR PHOTO RATES 5
The rate constants scale approximately with the solar flux, i.e., with r-2, where r is
the heliocentric distance in AU. At small r the rate constants can increase more rapidly
than r- because of the contributions from thermally excited states.
2
2. Solar Flux
The solar flux for the quiet Sun has been compiled from many pUblications. To provide
better resolution, it was sometimes necessary to interpolate by prorating the unresolved
portions of flux measured in large wavelength intervals to smaller bins and then add the
measured flux from emission lines with wavelengths that fall into these bins. From 0 to
A, A
10 data from Swider (1969) were used. In the interval 10 to 280 measured fluxes
were taken from Hinteregger (1970). From 270 to 1163 A the data from Hall and
Hinteregger (1970) were interpolated. In the range from 1163 to 7350 A data from
Ackerman (1971) were used with a correction by Simon (1974) in the interval 1961 to
2299 A. Finally, from 7350 to 140000 A the data published by Iqbal (1983) were used.
There are 324 solar flux bins. Figure 1 presents this solar flux as number of photons
A-I.
cm - Figure 2 shows the solar flux for the quiet Sun in the UV part of the
2 S - 1
spectrum and Figure 3 presents the ratio of the irradiances of the active to that of the
quiet Sun from Hinteregger et al. (1981), as presented by Lean (1987), in the same
spectrum range.
1 (1°
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LOG WAVELENGTH A
Fig. 1. The solar flux at 1 AU heliocentric distance for the quiet Sun presented as log number of photons
cm -2 S - 1 A-I vs log wavelength in A.
6 W. F. HUEBNER ET AL.
1000 1500 2000 2500
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'DO '000 1500 2000 2500 lOOO
WAVELENGTH A
Fig. 2. The solar UV flux at I AU heliocentric distance for the quiet Sun presented as log number of
photons cm -2 S - 1 A-I vs wavelength in A up to 2941 A.
500 1000 1500 2000 2500 30?p
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Fig. 3. The ratio of the flux of the active Sun to that of the quiet Sun vs wavelength in A up to
2941 A.