%0 Journal Article %1 Kohler:2005p831 %A Kohler, S %A Allan, M %A Kelso, H %A Henderson, D %A McKendrick, K %D 2005 %J Journal of Chemical Physics %K imported %N 2 %P -- %R Artn 024712 Doi 10.1063/1.1835268 %T The effects of surface temperature on the gas-liquid interfacial reaction dynamics of O(P-3) plus squalane %U http://links.isiglobalnet2.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=mekentosj&SrcApp=Papers&DestLinkType=FullRecord&DestApp=WOS&KeyUT=000226699000057 %V 122 %X OH/OD product state distributions arising from the reaction of gas-phase O(P-3) atoms at the surface of the liquid hydrocarbon squalane C30H62/C30D62 have been measured. The O(P-3) 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(P-3) 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. (C) 2005 American Institute of Physics.

@article{Kohler:2005p831, abstract = {OH/OD product state distributions arising from the reaction of gas-phase O(P-3) atoms at the surface of the liquid hydrocarbon squalane C30H62/C30D62 have been measured. The O(P-3) 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(P-3) 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. (C) 2005 American Institute of Physics.}, added-at = {2010-06-22T19:38:37.000+0200}, affiliation = {Kohler, SPK Heriot Watt Univ, Sch Engn {\&} Phys Sci, Edinburgh EH14 4AS, Midlothian, Scotland Heriot Watt Univ, Sch Engn {\&} Phys Sci, Edinburgh EH14 4AS, Midlothian, Scotland}, author = {Kohler, S and Allan, M and Kelso, H and Henderson, D and McKendrick, K}, biburl = {https://www.bibsonomy.org/bibtex/20fa474677fa7a9f7f40649795bcd578b/gsmith}, date-added = {2010-03-10 16:47:32 -0500}, date-modified = {2010-03-10 16:48:22 -0500}, doi = {Artn 024712 Doi 10.1063/1.1835268}, interhash = {044b538c0dadf9c484c33adccb5868ab}, intrahash = {0fa474677fa7a9f7f40649795bcd578b}, journal = {Journal of Chemical Physics}, keywords = {imported}, label = {rec-number 1515}, local-url = {file://localhost/Users/geoffreysmith/Documents/Papers/Journal%20of%20Chemical%20Physics/2005/Journal%20of%20Chemical%20Physics,%20122,%20-%202005.pdf}, month = Jan, note = {893DH Times Cited:14 Cited References Count:57}, number = 2, pages = {--}, pmid = {000226699000057}, rating = {0}, timestamp = {2010-06-22T19:39:19.000+0200}, title = {The effects of surface temperature on the gas-liquid interfacial reaction dynamics of O(P-3) plus squalane}, uri = {papers://E88B624E-D406-46FF-9D95-BB9C1AAE3FDC/Paper/p831}, url = {http://links.isiglobalnet2.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=mekentosj&SrcApp=Papers&DestLinkType=FullRecord&DestApp=WOS&KeyUT=000226699000057}, volume = 122, year = 2005 }