飞秒脉冲作用下氯丙烯的多光子解离和电离动力学

摘要

The dissociation and photoionization dynamics of C3H5Cl were studied at 200,400,and 800 nm with femtosecond laser pulses.The time-of-flight mass spectra,laser power index and photoelectron images were recorded.At short wavelength (200 nm),ionization of the parent molecule was found to be the dominant channel,while other ions were generated by the dissociation of C3H5Cl+.With the shift to long wavelength (e.g.,800 nm),fragment ions became dominant,and were generated through the multiphoton ionization of neutral fragments after the photodissociation of C3H5Cl.These results imply that photodissociation plays a significant role at long wavelength,because neutral fragments are supposed to be generated from the intermediate states reached by 800 nm photons.At 400 nm,the dissociation on the intermediate states is also critical,but is not as high as that at 800 nm.Taken together,our results demonstrate that the dissociation/ ionization behaviors of allyl chloride are wavelength-dependent,and reveal the complex dynamics of allyl chloride at 200,400 and 800 nm.%利用飞秒激光脉冲,在200、400和800 nm下对氯丙烯(C3H5Cl)的光解离和电离动力学进行了研究.实验测量了氯丙烯在飞秒脉冲作用下的飞行时间质谱、光强指数以及光电子影像.结果发现在短波(200 nm)时,母体分子的电离为主要通道,而其他离子均来源于C3H5Cl+的解离.当波长移动到长波(800 nm)时,碎片离子就占据了主导.这些碎片离子来源于中性碎片的多光子电离过程,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,光解离过程起到非常重要的作用.这是因为800 nm可以激发分子达到能够产生中性碎片的中间态.在400 nm时,虽然中间态的解离过程仍然至关重要,但并没有在800 nm时明显.综上所述,本文的研究证实了氯丙烯的光解离/电离行为具有波长依赖性,并揭示了氯丙烯在200、400和800 nm飞秒激光作用下的复杂动力学过程.