Using high-order harmonics with momentum imaging techniques to study atomic and molecular dynamics

Laser-generated high-order harmonics provide a source of extreme-ultraviolet radiation with unique capabilities for probing atomic and molecular dynamics. Here we present the first studies that employ high harmonics in conjunction with coincidence momentum imaging (COLTRIMS) techniques for studies of molecular dynamics. We generate pulse at $\sim $ 43 eV photon energy by upconverting intense ($>$ 10$^{14 }$Wcm$^{-2})$ 25 fs laser pulses in an argon filled waveguide. These photons illuminate a cold molecular beam of CO, CO$_{2}$ or N$_{2}$, with the ion and electron products from ionization/dissociation detected using time-and-position resolved detectors. We obtain count rates as high as 0.25 per harmonic pulse, sufficient for a variety of studies. By employing pump-probe techniques, we can launch molecules into highly excited states near the molecular double-ionization threshold, from where the dynamics unfold along different channels. We also employ field-free impulsive molecular alignment to demonstrate for the first time the use of single photon excitation to obtain ion and electron angular distributions in the lab frame.