Electron Correlation in the Two-Color Photoionization and Laser Dissociation of H2+

Abstract

We have constructed, to our knowledge, a first of its kind two-color pulsed synchrotron (XUV) and strong field laser (IR) COld Target Recoil Ion Momentum Spectroscopy (COLTRIMS) experiment. We describe the design, operation, and commissioning experiments of the new machine. We also present the first scientific results from a two color experiment: the photoionization of H2 with 18.49eV and 17,9eV XUV photons from the Advanced Light Source (ALS) at Lawrence Berkeley National Lab (LBNL) in the presence of a strong laser field (1:2eV , 1 1012W=cm2). We investigated the effects of the strong field on all aspects of the photoionization and subsequent dissociation processes proceeding directly from the single ionization or driven by the strong laser field. We employ statistical background subtraction as well as comparison between long and overlapped XUV-laser pulse configurations to sensitively observe changes to energy spectra and angular distributions of the photoelectron and the dissociated proton. We report observations of ponderomotive shifts in the photoelectron energy. However, we report no observation of interference fringes from light induced conical intersections that are expected to be present. Additionally, we report on possible hints of asymmetric proton emission in the laser driven dissociation from the retro-action of the photoelectron.