Hydrocarbon-atomic oxygen interactions occur in Earth's upper atmosphere because of venting and outgassing of various hydrocarbon species from space vehicles.  These interactions are especially important around the mesopause because the O atom density peaks near 1012 atoms/cm3. Since the interactions occur at very high collision speeds, product distributions may be different from those occuring under more moderate conditions.  In the present work, laser spectroscopic measurements of the vibrational temperatures of primary and secondary products of the C2H4 + O(3P) reaction will be presented. The experiments are conducted in a 1 meter reaction cell pumped by a roughing pump. Ethylene gas, an O-atom precursor (either NO2 or O3), and a bath gas of Ar and/or Xe are introduced into the cell using traditional flow techniques at a pressure of roughly 10 torr. The O-atom precursor is photodissociated by a Nd:YAG laser pulse (355 nm for NO2 or 266 nm for O3) to form atomic oxygen at varying kinetic energies. Transient diode laser absorption spectroscopy using a mid IR diode laser beam that is coincident with the Nd:YAG pulse is used to probe the reaction products. Detection will be done using a liquid nitrogen cooled InSb or MCT detector.  Vibrational temperatures of the products from the reaction at different collision energies will be compared.

Product distributions following hyperthermal collisions between C2H4 and O(3P)

245th National Meeting (2013)

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