High-harmonic spectroscopy of laser-driven nonadiabatic electron dynamics in the hydrogen molecular ion

Abstract

We theoretically explore a mechanism resulting in a minimum in the high-harmonic spectrum of a hydrogen molecular ion driven at extended internuclear distances by a mid-infrared laser source. Our analysis identifies this minimum to be a signature of the transient localization of the electron upon alternating nuclear centers and is representative of dynamics occurring exclusively at the time of ionization. We further demonstrate the sensitivity of this spectroscopic feature to driving field parameters as well as its robustness to distributions of laser field intensities and internuclear distances. Finally, we show how variations in the nonadiabatic dynamics induced by the ramping driving field can be imaged through changes in the number and locations of minima in the spectra.