Mapping molecular dynamics (Na2) in intense laser fields: another dimension to femtochemistry

Time-resolved photoelectron spectroscopy in combination with femtosecond pump–probe and molecular beam techniques is used to map the vibrational wavepacket motion along the internuclear coordinate. Using an attenuated femtosecond pump pulse and a probe pulse with variable intensity, the influence of high laser fields on the molecular potential is detected sensitive to the internuclear distance. We observe electronic transitions at non-Franck–Condon allowed areas which are attributed to light-induced potentials.