Darmstadt 2008 – scientific programme
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A: Fachverband Atomphysik
A 20: Experiments with FLASH and FEL perspectives: an overview
A 20.2: Talk
Thursday, March 13, 2008, 11:30–11:45, 3C
Two-photon ionization of neon at 91 eV photon energy — •Ulrike Frühling1, Marek Wieland2, Elke Plönjes-Palm1, Michael Gensch1, and Markus Drescher2 — 1Desy, Hamburg — 2Universität Hamburg
For measurement of the temporal properties of optical pulses the nonlinear response of an optical medium on two optical fields of different or the same color is often used to realize cross- or autocorrelation schemes. The observation of nonlinear processes e.g. multiphoton-ionisation induced by short-pulse coherent extreme ultraviolet (XUV) radiation opens up the possibility of applying these correlation techniques in the XUV range. We have studied two-photon ionization of neon by photoelectron spectroscopy at the soft-x-ray free-electron laser in Hamburg (FLASH). The photon energy was 91 eV. The XUV-beam was focused using a multilayer mirror to irradiance levels of up to 1014W/cm2, leading to features in the electron spectrum which can be attributed to nonlinear processes.