Multiphoton Ion Pair Spectroscopy (MPIPS) with Ultrashort Laser Pulses for the H2 Molecule

Abstract

Time-dependent Schrödinger equation, TDSE, simulations have been performed in order to prepare and study via MPIPS the evolution of vibrational wave packets on the ion pair electronic state potentials B''B1Sigma(u)(+) and Hh1Sigma(g)(+) of the H2 molecule. Using ab initio potential surfaces and transition moments, we present two- and three-photon excitation schemes with ultrashort pulses (tau <or= 10 fs) to prepare coherent superpositions of the two ion pair H(+)H(-) and H(-)H(+) states from the doorway B1Sigma(u)(+) state, which result from the strong radiative coupling between these two electronic states. The simulations are used to estimate the time evolution and recursion times of vibrational wave packets at large internuclear distances, usually not accessible by single-photon spectroscopy. Conditions for the localization of the ion pair states are proposed.