Time-resolved measurements with intense ultrashort laser pulses: A 'molecular movie' in real time

Abstract

We report on the high-resolution multidimensional real-time mapping of H2+ and D2+ nuclear wave packets performed employing time-resolved three-dimensional Coulomb explosion imaging with intense laser pulses. Exploiting a combination of a "reaction microscope" spectrometer and a pump-probe setup with two intense 6-7 fs laser pulses, we simultaneously visualize both vibrational and rotational motion of the molecule, and obtain a sequence of snapshots of the squared ro-vibrational wave function with time-step resolution of ∼ 0.3 fs, allowing us to reconstruct a real-time movie of the ultrafast molecular motion. We observe fast dephasing, or 'collapse' of the vibrational wave packet and its subsequent revival, as well as signatures of rotational excitation. For D 2+ we resolve also the fractional revivals resulting from the interference between the counter-propagating parts of the wave packet. © 2007 IOP Publishing Ltd.