The reaction of hydrogen atoms with ozone generates hydroxyl radicals (OH) in vibrational levels between v=5 and 9. This reaction occurs naturally in the upper region of the mesophere, generating strong infrared flourescence from the vibrationally excited OH. In this altitude region, the intensity and spectrum of the emission depend on both the radiative and the collisional properties of the vibrationally excited OH. Under a previous grant the PI developed new laser-based methods of measuring the rate constants and relaxation pathways of these highly vibrationally excited radicals. In the work supported by this grant the new technique will be applied to determining OH rate constants that are at atmospheric importance and directly applicable to the conditions encountered by the excited OH in the mesosphere. These experiments are technically challenging, but the experimental technique has been shown to be feasible, and important quantitative measurements can be extracted.
