Vibrationally resolved strong-field dissociation ofD2+in ion beams

Abstract

Photodissociation of $\mathrm{D}_{2}{}^{+}$ molecular ions in a beam from an ion source has been studied with $785\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ intense femtosecond laser pulses. Using a high-resolution velocity imaging technique, the neutral fragments from single vibrational levels of the $\mathrm{D}_{2}{}^{+}$ molecules have been resolved. The effects of one- and net two-photon bond softening: level shifting, vibrational trapping, and molecular alignment are observed in the kinetic energy and angular distributions and are discussed in detail. In comparison with our previous study on $\mathrm{H}_{2}{}^{+}$, we observe smaller widths of the peaks in the kinetic energy distributions of the $\mathrm{D}_{2}{}^{+}$ fragments from single vibrational levels. We attribute this to the longer lifetimes of $\mathrm{D}_{2}{}^{+}$ vibrational states in the light-induced potentials. The width of the angular distributions increases for lowest fragment energies, which suggests vibrational trapping of the levels close to the three-photon crossing.