Other
Scientific paper
Dec 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010agufmsa43a1751p&link_type=abstract
American Geophysical Union, Fall Meeting 2010, abstract #SA43A-1751
Other
[0310] Atmospheric Composition And Structure / Airglow And Aurora, [0340] Atmospheric Composition And Structure / Middle Atmosphere: Composition And Chemistry, [0355] Atmospheric Composition And Structure / Thermosphere: Composition And Chemistry
Scientific paper
Emission from H2O molecules in the 6.3-μm band is an important atmospheric observable, because it allows the atmospheric water vapor density profiles to be derived from measured emission intensities. This procedure is reliable only if the collisional processes that affect this emission are accounted for accurately. The two most important such processes involve vibrationally excited O2 molecules: (1) O2(X 3Σg-, υ = 1) + O(3P) ↔ O2(X 3Σg-, υ = 0) + O(3P) and (2) O2(X 3Σg-, υ = 1) + H2O ↔ O2(X 3Σg-, υ = 0) + H2O(ν2). Process (1) was previously investigated in our laboratory using an experimental approach in which O2(X 3Σg-, υ = 1) is probed indirectly, through its interaction with O2(a1Δg, υ = 1), and the latter species is probed via resonance-enhanced multiphoton ionization (REMPI). Both oxygen atoms and O2(a1Δg, υ = 1) are produced by laser photolysis of ozone at 285 nm. With O2 present in the system, O2(X 3Σg-, υ = 1) is rapidly produced in the near-resonant process O2(a1Δg, υ = 1) + O2(X 3Σg-, υ = 0) ↔ O2(X 3Σg-, υ = 1) + O2(a1Δg, υ = 0). The long-time decay of the experimental REMPI signals reflects the kinetics of the coupled O2(X 3Σg-, υ = 1) and O2(a1Δg, υ = 1) populations, and the decay rate is controlled primarily by process (1). This approach proved to be more practical than the one in which O2(X 3Σg-, υ = 1) is probed directly, and it allows for a number of other collisional processes to be investigated by a simple variation of experimental parameters. However, extraction of the rate coefficient for process (1) from the data is nontrivial. We report a refined data analysis approach, based on a combination of numerical and analytical modeling, which allows contributions of competing processes to the measured kinetics to be identified and quantified. This improved data analysis results in a more reliable and more tightly constrained value for the rate coefficient for process (1) compared with the previously reported values of this quantity. Details of the modeling approach will be presented, together with new recommended values of the rate coefficients for process (1) at temperatures 160-295 K and for collisional processes involving O2(a1Δg, υ = 1) and colliders O2, O(3P), CO2, and N2. We will also discuss our current efforts to measure the rate coefficient for process (2) using an experimental approach based on stimulated Raman scattering pumping of O2 to the υ = 1 level and detection of the resulting infrared emission from H2O(ν2). This work was supported by the NASA Geospace Science Program.
Copeland Richard A.
Pejaković Dušan A.
Saran D. V.
No associations
LandOfFree
Relaxation of O2(X 3Σg-, υ = 1) by Atmospherically Relevant Colliders does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Relaxation of O2(X 3Σg-, υ = 1) by Atmospherically Relevant Colliders, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Relaxation of O2(X 3Σg-, υ = 1) by Atmospherically Relevant Colliders will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1505818