Probing two-center interference in H2+using chirped pulses

The influence of intermediate resonant dissociative channels in the few-photon ionization dynamics of H+2is demonstrated in a pump-probe scenario. Two-photon ionization of H+2 by two sequentially applied pumpand probe vuv/fs 1011 W/cm2 laser pulses is reported. The kinetic energy distribution of the ejected protons iscalculated by solving the time-dependent Schr¨odinger equation within the Born-Oppenheimer approximation,including the electronic three-dimensional and vibrational one-dimensional motion. Population is effectivelytransferred from the 1sσg to the 3pσu potential surface, via resonant one-photon absorption, by applying achirped pump pulse. The molecule is ultimately ionized by the probe pulse. It is found that a double-peakedstructure appears in the resulting kinetic energy release spectra of the nuclear fragments. A correspondingmodulated structure also appears in the dissociative channels, merely demonstrating that the double-peakedstructure in the spectra originates from the molecular 1sσg-3pσu electronic dynamics, and an inherent twocenterinterference in the underlying electric dipole coupling. It turns out that the dipole coupling between the1sσg and 3pσu electronic states vanishes at an internuclear distance of 2.25 a.u., i.e., close to the equilibriuminternuclear separation. The resulting node in the R-dependent dipole coupling imposes a minimum in thecorresponding kinetic energy release spectra of the dissociating nuclei. By creating a negative or positive chirpin the applied pump pulse, it is found that the modulations can be made more or less salient