Laboratory Study of Collisions of Vibrationally Excited OH with O2 and O

Sri International, Menlo Park CA

Investigators

Abstract

This proposal addresses three needs of the Aeronomy community and the TIMED program. i) Determine the removal rates for the OH (u = 7, 8, and 9) levels by O2 at mesospheric temperatures to the required accuracy of15%. ii)Measure the removal rate of various levels of vibrationally excited OH by O atoms to the required accuracy of 50%. iii) Study the pathways of energy disposition from the collisional removal of vibrational energy from the OH(u = 7, 8, and 9) levels. Currently, the collisional removal rates of the OH (u= 7, 8, and 9) levels by O2 are only known, through the PI's previous measurements at room temperature, to an accuracy of 29%, 13% and 65%, respectively. These measurements also showed that the rate for OH (u = 10) removal by 02 increased by 37% as the temperature was reduced from 310 K to 223 K. There are no measurements or calculations of the collisional removal rates for vibrational levels of OH by O atoms. Finally, the mechanisms for vibrational energy removal have only been deduced form modeling studies, with uncertain results. Thus, the proposed laboratory measurements are needed if the SABER experiment of the TIMED program is to meet its accuracy goals and to understand the intensity of OH emission in the atmosphere