Smits M, Westwood NP, Peel JB, Visscher L
Laboratory for Physical Chemistry, University of Amsterdam, The Netherlands.
Faraday Discuss. 2000(115):259-69; discussion 303-30. doi: 10.1039/a909273k.
A (2 + 1) one-colour resonance-enhanced multiphoton ionisation study is carried out on the C 2 sigma- state of the ClO radical in the one-photon energy range 29,500-31,250 cm-1. The ClO radical is produced by one-photon photolysis of ClO2 employing 359.2 nm photons derived from a separate laser. In this way a significant concentration of vibrationally excited ClO in its spin-orbit split X 2 pi omega (omega = 3/2 or 1/2) electronic ground state is produced. In addition to mass-resolved excitation spectra, kinetic-energy resolved photoelectron spectra for the X 3 sigma-(v+)<--C 2 sigma-(v' = 3-5) transitions are measured. These transitions are not completely Frank-Condon diagonal, and indicate a decrease in bond length on removal of the Rydberg electron from the C 2 sigma- state. In addition to an unambiguous assignment of the C 2 sigma- state, valuable information is obtained on the degree of vibrational excitation with which the nascent ClO radical is formed in the photolysis of ClO2. Analysis of the photoelectron spectra is supported by Franck-Condon calculations based on potential energy curves either from experimental spectroscopic parameters, or obtained by theoretical ab initio methods.
在29,500 - 31,250 cm⁻¹的单光子能量范围内，对ClO自由基的C 2σ⁻态进行了（2 + 1）单颜色共振增强多光子电离研究。ClO自由基是通过使用来自另一台激光器的359.2 nm光子对ClO₂进行单光子光解产生的。通过这种方式，产生了大量处于其自旋 - 轨道分裂的X 2πω（ω = 3/2或1/2）电子基态的振动激发态ClO。除了质量分辨激发光谱外，还测量了X 3σ⁻(v +)←C 2σ⁻(v' = 3 - 5)跃迁的动能分辨光电子能谱。这些跃迁并非完全是弗兰克 - 康登对角的，并且表明从C 2σ⁻态移除里德堡电子时键长会减小。除了对C 2σ⁻态进行明确的归属外，还获得了关于在ClO₂光解过程中新生ClO自由基形成时的振动激发程度的有价值信息。基于来自实验光谱参数的势能曲线或通过理论从头算方法获得的势能曲线进行的弗兰克 - 康登计算，为光电子能谱的分析提供了支持。
