飞秒光电子影像技术对氯丙烯分子的光电离/解离机理的研究

飞秒光电子影像技术结合飞行时间质谱对氯丙烯（C3H5Cl）在200 nm、400 nm、800 nm飞秒脉冲下的光电离/解离机理进行了研究。实验结果表明氯丙烯的光电离/解离机理与激光波长存在依赖关系。分析发现，在短波长200 nm时，母体分子C3H5Cl以双光子电离为主要通道，而其他的碎片离子则来源于C3H5Cl+的解离。当波长向长波方向变化时，例如800 nm时，C3H5Cl中间态的解离就开始占主导地位，碎片离子的信号也相应增强。此外，光电子能谱进一步证实了在400 nm和800 nm时存在来源于中性碎片的光电子，而这些中性碎片又是由C3H5Cl的中间态直接解离而产生的。这意味着，在长波400 nm和800 nm时，母体分子可能被激发到寿命较短的中间解离态，从而解离产生中性碎片，导致光解离过程在长波段占有重要角色。

Photoionization/photodissociation mechanisms of allyl chloride by femtosecond photoelectron imaging technology

Based on femtosecond photoeletron imaging technique and time-of-flight mass spectroscopy,the photoionization/photodissociation mechanisms of allyl chloride (C3H5Cl) at 200,400,800 nm femtosecond laser pulses are investigated.Results show that the photoionization/photodissociation mechanisms of C3H5Cl have dependence on laser wavelength.At short wavelength 200 nm,two-photon ionization is the dominant channel of parent molecule C3H5Cl,and other fragment ions are generated by dissociation of CaH5Cl+.When it shifts to longer wavelength,such as 800 nm,dissociation from intermediate states of C3H5Cl starts to play a leading role,and the signals of fragment ions are also enhanced.Photoelectron spectra further confirm that there are photoelectrons coming from neutral fragments at 400 nm and 800 nm,and they are generated from dissociation of the intermediate states of C3H5Cl.It implies that at 400 nm and 800 nm,the parent molecule may be excited to intermediate dissociation states with shorter life-time and produce neutral fragments,which makes the process of light dissociation play an important role in the long waveband.