TY  - JOUR
U1  - Zeitschriftenartikel, wissenschaftlich - begutachtet (reviewed)
A1  - Köhler, Sven P. K.
A1  - Allan, Mhairi
A1  - Kelso, Hailey
A1  - Henderson, David A.
A1  - McKendrick, Kenneth G.
T1  - The effects of surface temperature on the gas-liquid interfacial reaction dynamics of O(³P)+squalane
JF  - The Journal of Chemical Physics
N2  - OH/OD product state distributions arising from the reaction of gas-phase O(³P) atoms at the surface of the liquid hydrocarbon squalane C₃₀H₆₂/C₃₀D₆₂ have been measured. The O(³P) atoms were generated by 355 nm laser photolysis of NO₂ at a low pressure above the continually refreshed liquid. It has been shown unambiguously that the hydroxyl radicals detected by laser-induced fluorescence originate from the squalane surface. The gas-phase OH/OD rotational populations are found to be partially sensitive to the liquid temperature, but do not adapt to it completely. In addition, rotational temperatures for OH/OD(v′=1) are consistently colder (by 34±5 K) than those for OH/OD(v′=0). This is reminiscent of, but less pronounced than, a similar effect in the well-studied homogeneous gas-phase reaction of O(³P) with smaller hydrocarbons. We conclude that the rotational distributions are composed of two different components. One originates from a direct abstraction mechanism with product characteristics similar to those in the gas phase. The other is a trapping-desorption process yielding a thermal, Boltzmann-like distribution close to the surface temperature. This conclusion is consistent with that reached previously from independent measurements of OH product velocity distributions in complementary molecular-beam scattering experiments. It is further supported by the temporal profiles of OH/OD laser-induced fluorescence signals as a function of distance from the surface observed in the current experiments. The vibrational branching ratios for (v′=1)/(v′=0) for OH and OD have been found to be (0.07±0.02) and (0.30±0.10), respectively. The detection of vibrationally excited hydroxyl radicals suggests that secondary and/or tertiary hydrogen atoms may be accessible to the attacking oxygen atoms.
KW  - Oberflächentemperatur
KW  - Reaktionsdynamik
KW  - Squalan
KW  - Laserphotolyse
KW  - Hydroxyl
Y1  - 2005
UN  - https://nbn-resolving.org/urn:nbn:de:bsz:960-opus4-22933
SN  - 0021-9606
SS  - 0021-9606
U6  - https://doi.org/10.25968/opus-2293
DO  - https://doi.org/10.25968/opus-2293
VL  - 122
PB  - AIP Publishing
ER  -