Simultaneous real-time tracking of wave packets evolving on two different potential curves inH2+andD2+

Abstract

We have used intense few-cycle laser pulses in a pump-probe arrangement to directly map, with high time resolution, the simultaneous evolution on two different potential curves of wave packets created when ${\mathrm{H}}_2$ $\left({\mathrm{D}}_2\right)$ molecules were ionized by a strong laser field. The experimental “snapshots” were obtained by measuring in coincidence the kinetic energy distribution of the proton (deuteron) pairs produced in the Coulomb explosion of the $\mathrm{H}_2{}^{+}$ $\left(\mathrm{D}_2{}^{+}\right)$ molecular ions as a function of the time delay between the pump and the probe pulses. The time resolution was sufficient to reveal not only the evolution of the wave packet centroid but also the fundamentally wavelike features of the packets. A full quantum calculation of observed nuclear motion is in good agreement with the measured spectra.