Third order effect of postionization population redistribution in strong field

Xiangxu Mu,Hanwei Yang,Jiechao Feng,Keyu Guo,Zijian Lü,Ming Zhang,Haitan Xu,Min Li ,Song Bin Zhang ,Lu Zheng

doi:10.1103/physrevresearch.3.043144

Abstract

In strong field ionization, the pump pulse not only photoionizes the molecule, but also drives efficient population exchanges between its ionic ground and excited states. In this study, we investigate the population dynamics after strong field molecular photoionization, using angular distribution of dissociative fragments. Our results reveal that the first and third order processes of the post-ionization population redistribution mechanism (PPRM) in the ion can be disentangled and classified by its angle-resolved kinetic energy release (KER) spectra. We demonstrate that the imprints of PPRM in the KER spectra can be used to determine the branching ratio of the population exchange pathways of different orders, by exploiting the pump-intensity-dependent variation of the spectra.

Highlights

The photoionization and dissociation of molecules induced by intense femtosecond laser pulse are fundamental physical processes of light-matter interactions [1,2]
Our results reveal that the first and third order processes of the post-ionization population redistribution mechanism (PPRM) in the ion can be disentangled and classified by its angle-resolved kinetic energy release (KER) spectra
We study the third order effect in postionization population redistribution which can be disentangled from the usual first order process using kinetic energy release spectra as a function of the angle between the molecular alignment axis and the linear polarization of the ionization pump pulse

Summary

Introduction

The photoionization and dissociation of molecules induced by intense femtosecond laser pulse are fundamental physical processes of light-matter interactions [1,2]. The ionization and dissociation of few-electron molecules, such as H2, have been exhaustively studied [14,15,16,17,18,19,20,21,22,23,24,25,26], e.g., Ref. [28] provides a complete quantum modelization for angle-resolved kinetic energy release (KER) spectra of photofragments resulting from intense field dissociation with an assumption that transition dipole vector is parallel to the molecular axis. The resulting post-ionization population redistribution mechanism (PPRM) has proven to be important in many scenarios and applications of strong field physics [32,33,34,35,36]. Resolving the dynamics of PPRM is indispensable to devise new control mechanisms in these applications

Methods

Results

Conclusion