Carbonyl and hydrogen sulfide abundance in Venus atmosphere determined from infrared spectr

Cruikshank, D. P.

English

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No. 98 SULPHUR COMPOUNDS IN THE ATMOSPHERE OF VENUS 
XI: UPPER LIMITS FOR THE ABUNDANCE OF COS AND HzS 
by D. P. CRUIKSHANK 
October 20,1967 
ABSTRACT 
Laboratory spectra of small amounts of carbonyl sulfide and hydrogen sulfide are discussed relative to their abundance 
in the Venus “tmqsphere. The upper limits to the mixing ratios relative to a two-way transmission in the Venus atmosphere, 
4 km-atn. af -02. are: COS < 10-6, and HnS < 2 x 10-4. 
1. Introduction 
his paper presents results of attempts to estimate 
sulfide (COS) and hydrogen sulfide (H2S) in the 
Venus atmosphere using new spectroscopic data. 
Such limits are especially relevant to the Venus 
problem because of the computcr models of chemical 
and thermodynamic equilibria in planetary atmo- 
spheres (Lewis 1968, and Lippincott et al. 1967) 
that are now available. The sulfur gases also relate 
directly to the current level of volcanic activity on 
Venus. 
T the upper limits of the abuw mces of carbonyl 
2. Carbonyl Sulfide 
Tracings of the near-infrared spectrum of COS 
were published by Kuiper and Cruikshank (1964). 
The strongest band in the region 0.9-2.6 y is cen- 
tered at 2.44 p. Ncw tracings of this aiid adjacent 
bands with resolution (h /Ah)  7000 are shown in 
Figurc 1 for different amounts of the gas from 4.7 
nim-atm to 50 mm-atm, all at 705 mm Hg pressure 
and room temperature. No COS is detected in the 
Venus atmosphere where the laboratory spectra are 
cornparcd with the Venus tracings of Kuiper (1962), 
Moroz (1964), m! ‘ ’ r and Fcrbes (1967). 
The latter are s O +  .’,I- ” - x i s =  the heavy 
telluric water-vap ~ . ” ens -: ly reduced. 
An uppcr k * I  c f  . i r  .;, I: I . .  -;;sy trans- 
mission in the Venus atmosphere may be established 
on the basis of this comparison. For 4 km-atm COZ 
in the Venus atmosphere two-way transmission, this 
corresponds to an upper limit to the mixing ratio of 
10-6. 
3. Hydrogel8 Sulfide 
The test for H,E is less sensitive than for COS 
because of contamination of the Venus spectrum by 
many bands of CO,. The ultraviolet electronic bands 
occur as a broad continrim from 1900-2700 A 
(Herzberg 1966, p. 489) and are therefore unsuit- 
able for our purpose. A strong vibrational band at 
1.58 y lies on a branch of the 301 band of Ct3O2 
( 1 S714 y )  which is very strong in the Venus spec- 
trum. The 101 band of H2S at 1.94 y is similarly 
blended with CO, in the atmospheres of the earth and 
Venus, and with telluric H20. A rough upper limit 
of 1 m-atm for H2S can be established, however, 
using Kuiper’s spectra and those of Moroz (1964) 
with the H,S sp-ctra of Cruikshank (1967). Rela- 
tive to 4 km-atm CO, in the Venus atmosphere, this 
corresponds to an upper limit in the mixing ratio of 
2 x 10-4. 
Acknowledgment. The planetary program at this 
Laboratory is supported by National Aeronautics 
and Space Administration Grant NsG 161-61. 
199 
https://ntrs.nasa.gov/search.jsp?R=19690003312 2020-03-12T08:10:10+00:00Z
200 D. P. CRUIKSHANK 
I I I I 
I 
Fig. I A portion of the infrared spectrum of COS showing the development of the bard with various amounts of gas. 
(a) Blank run with no COS but 4.36 m laboratory air in optical path, including spectrometer, (b)  same air path with 4.7 
mm COS at p = 1 atm, (c) air path with 7.1 mm COS at p = 1 atm, (d) air path with 50 mm COS at p = 1 atm. B-spec- 
trometer slit 0.05 mm, detector width 0.05 mm. 
REFERENCES 
Cruikshank, D. P. 1967, “Laboratory Spectra for 
Testing the Presence of Minor Constituents in 
Planetary Atmospheres, 11: CrH2, C2H4, C2Ho, 
pectra and Elec- 
tronic Structure of Polyatomic Molecules, Vol. 
111 in Molecular Spectra and Moleculur Struc- 
lure (Princeton, N.J.: D. Van Nostrand Co.). 
Kuiper, G. P. 1962, “Infrared Spectra of Stars and 
Planets, I: Photometry of the Infrared Spectrum 
of Venus, 1-2.5 Microns,” Comm, LPL, 1, 83- 
117. 
Kuiper, G. P., and Forbes, F. F. 1967, “High-Alti- 
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CHBSH, CHaNHz, HZS,’’ (70;. ;;’ CPL, 6, 1-30. 
Hetzberg, G. 1966, EIectroni, 
1-2.5 Microns, Resolution 20 cm-l,” Comm. 
Kuiper, G. P., and Cruikshank, D. P. 1964, “Lab- 
oratory Spectra for Testing the Presence of 
Minor Constituents in Planetary Atmospheres, 
I: CH4, NH:%, NnO, CO, COS, Region 1-2.5 y,” 
Comm. LPL, 2, 141-165. 
Lewis, J. S. 1968, “An Estimate of the Surface Con- 
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Lippincott, E. R., Eck, R. V., Dayhog, M. O., and 
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Sulphur compounds in the atmosphere of Venus. 2 - Upper limits for the abundance of carbonyl sulfide and hydrogen sulfide

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