Ng Cheuk-Yiu
Department of Chemistry, University of California, Davis, California 95616; email:
Annu Rev Phys Chem. 2014;65:197-224. doi: 10.1146/annurev-physchem-040412-110002. Epub 2013 Dec 13.
Recent advances in high-resolution photoionization, photoelectron, and photodissociation studies based on single-photon vacuum ultraviolet (VUV) and two-color infrared (IR)-VUV, visible (Vis)-ultraviolet (UV), and VUV-VUV laser excitations are illustrated with selected examples. VUV laser photoionization coupled with velocity-map-imaging threshold photoelectron (VMI-TPE) detection can achieve comparable energy resolution but has higher-detection sensitivities than those observed in VUV laser pulsed field ionization photoelectron (PFI-PE) measurements. For molecules with known intermediate states, IR-VUV and Vis-UV excitation schemes are highly sensitive for rovibronically selected and resolved PFI-PE studies. The successful applications of the VUV-PFI-PE, VUV-VMI-TPE, and Vis-UV-PFI-PE methods to state-resolved and state-to-state photoelectron studies of transient radicals and transitional metal-containing molecules are highlighted. The most recently established VUV-VUV pump-probe time-slice VMI photoion method is shown to be promising for state-to-state photodissociation studies of small molecules relevant to planetary atmospheres and for the fundamental understanding of photodissociation dynamics.
本文通过具体实例展示了基于单光子真空紫外（VUV）以及双色红外（IR）-VUV、可见（Vis）-紫外（UV）和VUV-VUV激光激发的高分辨率光电离、光电子和光解离研究的最新进展。VUV激光光电离与速度成像阈值光电子（VMI-TPE）检测相结合，可实现相当的能量分辨率，并且比VUV激光脉冲场电离光电子（PFI-PE）测量具有更高的检测灵敏度。对于具有已知中间态的分子，IR-VUV和Vis-UV激发方案对振转选择和分辨的PFI-PE研究具有高度敏感性。重点介绍了VUV-PFI-PE、VUV-VMI-TPE和Vis-UV-PFI-PE方法在瞬态自由基和含过渡金属分子的态分辨和态-态光电子研究中的成功应用。最新建立的VUV-VUV泵浦-探测时间切片VMI光电离方法被证明在与行星大气相关的小分子的态-态光解离研究以及光解离动力学的基础理解方面具有广阔前景。
