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A: Fachverband Atomphysik
A 25: Poster: Attosecond physics
A 25.2: Poster
Wednesday, March 14, 2012, 16:30–19:00, Poster.V
Quantitative measurement of phase matching in high harmonic generation — Sudipta Mondal1, •Frederic L. Condin1,2, Philipp L. Klaus1,3, Kristen Gould4, Benjamin Wilson4, Erwin D. Poliakoff4, and Carlos A. Trallero-Herrero1 — 1Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA — 2Eberhard Karls Universität Tübingen, D-72074 Tübingen, Germany — 3Institut für Kernphysik, Goethe-Universität Frankfurt am Main, D-60438 Frankfurt am Main, Germany — 4Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
Phase matching in high harmonic generation (HHG) is crucial for the quality and intensity of the generated harmonics and has important applications in modern attosecond science. We present a quantitative measurement of phase matching in HHG. In our experiments we simultaneously detect the generated harmonics and the produced ions as a function of laser focus position relative to a thin gas jet, intensity, and pressure for two pulse durations. The ion signal, the HHG yield, and the HHG yield divided by the squared ion signal serve as a measure of phase matching [cf. PRL 103, 073902 (2009) for a justification of the latter]. We find that the conditions for ideal phase matching drastically change when we switch from Gaussian to Bessel mode. The results have implications for our ongoing research efforts to use HHG as a spectroscopic method. Using the recently developed quantitative rescattering theory of HHG [PRA 80, 013401 (2009)], we want to extract photoionization cross sections from HHG spectra.