氢分子离子超快解离动力学研究进展

Progress of ultrafast dissociation dynamics for the hydrogen molecule ions

作为自然界中最简单的分子,氢分子离子(H_(2)^(+))及其同位素分子在超快物理研究中有着十分重要的地位.在过去的几十年中,人们已经对其解离现象做了大量的研究,并取得了一系列重要的成果.本文主要聚焦于H2+解离研究中理论和实验方面的最新进展,首先介绍处理解离问题的一般理论方法,接着综述3个相关热点研究问题,包括解离通道的干涉、电子与原子核的关联效应以及解离中的分子转动.这些最新的研究成果进一步拓展了人们对于小分子超快动力学的认识,为观测、理解和最终控制复杂的超快解离过程提供了一个很好的范例.

As the simplest molecules with only one electron and two nuclei in nature,H_(2)^(+)and its isotopes are of special importance and serve as benchmark systems for ultrafast science and technologies.Their dissociation in strong laser fields has attracted a lot of interests in past decades because it directly relates to the production of chemical reactions,and a series of great achievements have already been made successively under the cooperative efforts between the theoretical and experimental physicists.With the rapid technological development of lasers as well as the advanced experimental techniques in recent years,some new trends in this topic are presented.In this paper,we focus on recent research progress of experimental and theoretical works on hydrogen molecular ions dissociation.We first give a background information about past achievements,and then introduce general numerical methods to deal with dissociation,i.e.,the numerical simulation of the time-dependent Schrodinger equation(TDSE),and the combination of the strong field approximation and TDSE simulation.The latter was developed to investigate dissociative ionization of hydrogen molecules.Next three related hot research topics are reviewed sequentially,including interference between dissociation channels,photon energy sharing between electron and nuclei,and molecular rotation in dissociation.In detail,some strategies have been raised to control the unique electron localization after the molecular dissociation,which is due to the interference between the lowest two electronic states with opposite parities.In addition,the pump-probe technique was also utilized to observe electron localization dynamics in real time.However,interference of nuclear wave packets carrying different angular momenta in the same electronic state and ending with the same momentum contributes novel spiral momentum distribution under a circularly polarized laser pulse.The electron-nuclear correlation for different ionization mechanisms is mainly indicated in the joint energy spectra,which was extracted and explained by coincident measurement and various theoretical methods.The molecular rotation is generally assumed frozen in dissociation process,which is the common axial recoil approximation.However,recent theoretical and experimental researches show that the ultrafast electron dynamics may play roles in the molecular rotation though their timescales are significantly different.In conclusion,the studies of hydrogen molecular ions not only further deepen our understanding of ultrafast dynamics in small molecules,but also shed light on observing,understanding,and ultimately controlling complex chemical reactions.