00-085

Cover Page/Proposal Summary

ROSS-99    NRA 99-OSS-01

Date Due: 5/3/99

NASA PROCEDURE FOR HANDLING PROPOSALS

This proposal shall be used and disclosed for evaluation purposes only, and a copy of this Government notice shall be applied to any reproduction or abstract thereof. Any authorized restrictive notices that the submitter places on this proposal shall also be strictly complied with. Disclosure of this proposal for any reason outside the Government evaluation purposes shall be made only to the extent authorized by the Government.

Proposal Type: New Proposal

Proposal Category: Laboratory

Major Equipment Proposal? No

Do you intend to submit an Education/Public Outreach (E/PO) proposal? No

Proposal Title:
O2(a,b,c) in the nightglow of Venus

Abbreviated Proposal Title:
O2(a,b,c) in the nightglow of Venus

Principal Investigator:
Dr. Tom G. Slanger
Molecular Physics Lab
SRI International
333 Ravenswood Ave.
Menlo Park, CA 94025-3493
Phone: 650-859-2764   Fax: 650-859-6196   E-mail: slanger@mplvax.sri.com

SignatureDate
_________________________________________________

Co-Investigators and Collaborators:
Type    Name    Affiliation    E-mail
Sci Co-I   Dr. Richard A. Copeland   SRI International   rich@mplvax.sri.com


Proposal Summary:

We propose to determine the yields into three O2 electronically-excited states - denoted O2(a), O2(b), and O2(c) - following O2 photoexcitation close to the dissociation limit, in O2 and CO2 buffers. CO2 is the environment in which the Venus nightglow is generated, and two of the above states, O2(a,v=0) and O2(c,v=0), are strong Venus emitters, while O2(a,v=0) and O2(b,v=0) are strong emitters in the terrestrial atmosphere. We argue, based on our recent studies, that photoexcitation of O2 to levels near the dissociation limit is equivalent, in the sense of the evolution of the system, to the atom recombination process. A number of investigations, based on observations in both atmospheres, have led to problems of interpretation of emission intensities. Particularly in the case of the O2(a-X) 0-0 Infrared Atmospheric Band at Venus, it has been suggested that the emission intensity is much greater than expected. From the yields we will determine from laboratory measurements as well as the loss rate coefficients of the O2(c,v=0) level that we propose to measure, we will definitively show the major pathways by which O-atom recombination proceeds, which will then guide interpretation of past and future observations of planetary oxygen atmospheres.