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F. Ausfelder, H. Hippler, F. Striebel
The OH-yield in the reaction of O(1D) + CH4 under high pressure conditions up to 560 bar helium
The pressure dependence of the OH yield in the reaction O(1D) + CH4 has been investigated at room temperature in the pressure range from 4 to 560 bar of helium. O(1D)-atoms were generated by pulsed laser photolysis (PLP) of N2O and OH-radicals were detected by saturated laser induced fluorescence (SLIF). The OH-yield was determined relative to the OH yield in the reaction of O(1D) with H2 which is assumed to be unity and pressure independent. Within the pressure range of our experiments we found a constant OH-yield of (71±5)% in the reaction of O(1D) with methane. From the OH fluorescence lifetime at the highest pressures near 500 bar of helium we obtained the rate constant for the collisional deactivation of electronically OH radicals of kq(He) = (3±0.3)× 10-15 cm3 s-1, corresponding to a cross section of σq(He) = (2.1±0.2)× 10-20 cm2. The rate constant for collisional deactivation of vibrationally excited OH radicals in the electronic ground state OH(v=1) + He → OH(v=0) + He (reaction (5)) was determined to be k5(He) = (1.2±0.2)× 10-16 cm3 s-1.
Zeitschrift für Physikalische Chemie, Oldenbourg Wissenschaftsverlag
Print ISSN: 0942-9352
Volume: 214, 04/2000
Pages: 403