Correlation dynamics between electrons and ions in the fragmentation of D2 molecules by short laser pulses

We studied the recollision dynamics between the electrons and D2 1 ions following the tunneling ionization of D2 molecules in an intense short pulse laser field. The returning electron collisionally excites the D2 1 ion to excited electronic states; from there D2 1 can dissociate or be further ionized by the laser field, resulting in D1D or D1D, respectively. We modeled the fragmentation dynamics and calculated the resulting kinetic-energy spectrum of D to compare with recent experiments. Since the recollision time is locked to the tunneling ionization time which occurs only within a fraction of an optical cycle, the peaks in the D kinetic-energy spectra provide a measure of the time when the recollision occurs. This collision dynamics forms the basis of the molecular clock where the clock can be read with attosecond precision, as first proposed by Corkum and co-workers. By analyzing each of the elementary processes leading to the fragmentation quantitatively, we identified how the molecular clock is to be read from the measured kinetic-energy spectra of D and what laser parameters are to be used to measure the clock more accurately.