Temperature Dependence of the Vibrational Relaxation of OH(\upsilon = 1, 2) by O, O{_2}, and CO{_2}

Details Temperature Dependence of the Vibrational Relaxation of OH(\upsilon = 1, 2) by O, O{_2}, and CO{_2} Temperature Dependence of the Vibrational Relaxation of OH(\upsilon = 1, 2) by O, O{_2}, and CO{_2}

Jun 2009

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009mss..confeti06r&link_type=abstract

"International Symposium On Molecular Spectroscopy, 64th Meeting, Held 22-26 June, 2009 at Ohio State University. http://molspec

Astronomy and Astrophysics

Astrophysics

Atmospheric Species

Scientific paper

The hydroxyl radical is a key reactant in the energy budget of the atmospheres of terrestrial planets. In the Earth's upper atmosphere, OH(\upsilon ≤ 9) is formed by the H + O{_3} reaction. Recently, OH(\upsilon = 1 and 2) emission has been observed in the atmosphere of Venus. The magnitude of this emission is controlled by the competition between radiative decay and vibrational relaxation by the most abundant collider, CO{_2}. The data needed to model the emission rates of vibrationally excited OH radical include the vibrational quenching rates at temperatures relevant to the planetary atmospheres and the branching ratio between single- and multi- quantum relaxation steps. The latter parameter plays a crucial role in establishing the emission rates, as demonstrated by recent model calculations. Given the importance of rate constants and branching ratios for understanding the behavior of atmospheric OH on both Earth and Venus, we applied a two-laser approach to measure the rate constants for the vibrational relaxation of OH(\upsilon = 1, 2) by O-atoms, O{_2}, and CO{_2}. In these experiments, ozone is almost completely photolyzed at 248 nm and most of the resulting O(^{1}D) atoms quenched to O(^{3}P) by collisions with N{_2} and CO{_2}. A small fraction of O(^{1}D) reacts with H{_2}O, forming OH(\upsilon ≤ 2). The temporal evolutions of OH(\upsilon = 1, 2) are measured using laser induced fluorescence and kinetic simulations are used to extract the rate constants and the relaxation branching ratios. Experiments were performed at temperatures between 210 and 300 K. We find that the collisional removal rate constants for OH(\upsilon = 2) increase as the temperature decreases. The CO{_2} branching ratio indicates that most of OH(\upsilon = 2) relaxes to OH(\upsilon = 1) following collisions with CO{_2}, i.e., the cascading removal pathway is predominant.
This work was supported by NASA Geospace Science and Planetary Atmospheres Programs. The participation of H. Timmers was supported by an NSF Research Experiences for Undergraduates (REU) Program.
G. Piccioni et al., Astronomy & Astrophysics, 483, L29 (2008)
A. G. Garcia-Muñoz et al., Icarus, 176,75 (2005); X. Zhu and J. H. Yee, Icarus, 189, 136 (2007)

Affiliated with

Also associated with

No associations

Rating

Temperature Dependence of the Vibrational Relaxation of OH(\upsilon = 1, 2) by O, O{_2}, and CO{_2} 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 Temperature Dependence of the Vibrational Relaxation of OH(\upsilon = 1, 2) by O, O{_2}, and CO{_2}, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Temperature Dependence of the Vibrational Relaxation of OH(\upsilon = 1, 2) by O, O{_2}, and CO{_2} will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1642641