We report the first femtosecond time-resolved photoelectron spectroscopy study of 2-, 3- and 4-nitrobenzaldehyde (NBA) and nitrobenzene (NBE) in the gas phase upon excitation at 200 nm. In 3- and 4-NBA, the dynamics follow fast intersystem crossing within 1-2 picoseconds. In 2-NBA and NBE, the dynamics are faster (∼$\sim$0.5 ps). 2-NBA undergoes hydrogen transfer similar to solution phase dynamics. NBE either releases NO₂ in the excited state or converts internally back to the ground state. We discuss why these channels are suppressed in the other nitrobenzaldehydes.

中文翻译：

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硝基苯及其醛的时间分辨光电子能谱

我们报告了在200 nm激发时气相中的2-，3-和4-硝基苯甲醛（NBA）和硝基苯（NBE）的第一飞秒时间分辨光电子能谱研究。在3-NBA和4-NBA中，动力学遵循1-2皮秒内的快速系统间穿越。在2-NBA和NBE中，动态速度更快（〜$〜$0.5 ps）。2-NBA经历类似于溶液相动力学的氢转移。NBE要么以激发态释放NO ₂，要么内部转化为基态。我们讨论了为什么这些通道在其他硝基苯甲醛中被抑制。