PhysicoChimie des Processus de Combustion et de l'Atmosphère PC2A, University Lille 1, Cité Scientifique, Bât. C11, 59655 Villeneuve d'Ascq, France.
Chemphyschem. 2010 Dec 17;11(18):3867-73. doi: 10.1002/cphc.201000419.
The energy dependence of HO(2) radical formation from the irradiation of benzene (C(6)H(6)) in the presence of oxygen (O(2)) at 248 nm is studied. We investigate the origin of the HO(2) radicals, that is, whether they originate from the reaction of O(2) with products obtained by one- or two-photon excitation of C(6)H(6). The concentration-time profiles of HO(2) radicals are monitored by continuous-wave cavity ring-down spectroscopy (cw-CRDS) coupled to a laser photolysis reactor. HO(2) radicals are detected in the first vibrational overtone of the OH stretch at 6638.20 cm(-1), using a distributed feedback (DFB) diode laser. Two well-distinguished HO(2) radical-formation phases are observed: a fast initial formation of HO(2) radicals followed by a slower secondary formation. While the concentration of the initially formed HO(2) species increases linearly with the excitation energy, the concentration of the secondary slow HO(2) radicals appears to vary in accordance with a two-photon process.
在 248nm 波长的光辐照下，研究了苯（C(6)H(6)）在氧气（O(2)）存在下形成 HO(2)自由基的能量依赖性。我们研究了 HO(2)自由基的起源，即它们是否来自 O(2)与 C(6)H(6)的单光子或双光子激发产物的反应。通过连续波腔衰荡光谱（cw-CRDS）与激光光解反应器耦合，监测 HO(2)自由基的浓度-时间曲线。HO(2)自由基在 6638.20cm(-1)处的 OH 伸缩第一泛频处通过分布式反馈（DFB）二极管激光进行检测。观察到两种明显不同的 HO(2)自由基形成阶段：快速初始形成 HO(2)自由基，然后是较慢的次级形成。虽然最初形成的 HO(2)物种的浓度随激发能量线性增加，但次级慢速 HO(2)自由基的浓度似乎与双光子过程一致。
