The effects of surface temperature on the gas-liquid interfacial reaction dynamics of O(³P)+squalane
- 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.
Author: | Sven P. K. KöhlerORCiD, Mhairi Allan, Hailey Kelso, David A. Henderson, Kenneth G. McKendrick |
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URN: | urn:nbn:de:bsz:960-opus4-22933 |
DOI: | https://doi.org/10.25968/opus-2293 |
DOI original: | https://doi.org/10.1063/1.1835268 |
ISSN: | 0021-9606 |
Parent Title (English): | The Journal of Chemical Physics |
Publisher: | AIP Publishing |
Document Type: | Article |
Language: | English |
Year of Completion: | 2005 |
Publishing Institution: | Hochschule Hannover |
Release Date: | 2022/06/22 |
GND Keyword: | Oberflächentemperatur; Reaktionsdynamik; Squalan; Laserphotolyse; Hydroxyl |
Volume: | 122 |
Article Number: | 024712 |
Link to catalogue: | 1809791596 |
Institutes: | Fakultät II - Maschinenbau und Bioverfahrenstechnik |
DDC classes: | 660 Technische Chemie |
Licence (German): | ![]() |