Voronova Krisztina, Ervin Kent M, Torma Krisztián G, Hemberger Patrick, Bodi Andras, Gerber Thomas, Osborn David L, Sztáray Bálint
Department of Chemistry, University of the Pacific , Stockton, California 95211, United States.
Department of Chemistry, University of Nevada, Reno , Reno, Nevada 89557-0216, United States.
J Phys Chem Lett. 2018 Feb 1;9(3):534-539. doi: 10.1021/acs.jpclett.7b03145. Epub 2018 Jan 19.
We investigated the simplest alkylperoxy radical, CHOO, formed by reacting photolytically generated CH radicals with O, using the new combustion reactions followed by photoelectron photoion coincidence (CRF-PEPICO) apparatus at the Swiss Light Source. Modeling the experimental photoion mass-selected threshold photoelectron spectrum using Franck-Condon simulations including transitions to triplet and singlet cationic states yielded the adiabatic ionization energy of 10.265 ± 0.025 eV. Dissociative photoionization of CHOO generates the CH fragment ion at the appearance energy of 11.164 ± 0.010 eV. Combining these two values with ΔH(CH) yields ΔH(CHOO) = 22.06 ± 0.97 kJ mol, reducing the uncertainty of the previously determined value by a factor of 5. Statistical simulation of the CHOO breakdown diagram provides a molecular thermometer of the free radical's internal temperature, which we measured to be 330 ± 30 K.
我们使用瑞士光源处的新型燃烧反应光电子光离子符合（CRF - PEPICO）装置，研究了由光解产生的CH自由基与O反应形成的最简单的烷基过氧自由基CHOO。利用弗兰克 - 康登模拟对实验光离子质量选择阈值光电子能谱进行建模，包括向三重态和单重态阳离子态的跃迁，得出绝热电离能为10.265±0.025电子伏特。CHOO的离解光离子化在11.164±0.010电子伏特的出现能处产生CH碎片离子。将这两个值与ΔH(CH)相结合，得出ΔH(CHOO)=22.06±0.97千焦/摩尔，将先前测定值的不确定性降低了5倍。CHOO分解图的统计模拟提供了自由基内部温度的分子温度计，我们测得其为330±30开尔文。
