München 2004 – scientific programme

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A: Atomphysik

A 18: Multiphotonionisation II

A 18.4: Talk

Thursday, March 25, 2004, 17:15–17:30, HS 133

Single ionization of atoms in ultrashort intense laser pulses — •Artem Rudenko, Claus Dieter Schröter, Karl Zrost, Vitor L. B. de Jesus, Bernold Feuerstein, Robert Moshammer, and Joachim Ullrich — Max-Planck-Institut für Kernphysik, Heidelberg

Single ionization of atoms in very intense laser fields is usually discussed in terms of field or tunneling ionization. There, the active electron is assumed to be set free with almost zero kinetic energy via tunneling before it is accelerated, gaining drift energy in the oscillating laser field. This results in smooth and unstructured photoelectron energy distributions [1]. Recently, deviations from the simple tunneling picture were observed experimentally for the emission of the ultra low-energy electrons from Ne [2]. Following these experimental findings we performed systematic experimental studies for single ionization of He, Ne and Ar atoms by 23 fs and 6 fs laser pulses over a wide range of intensities (up to 2 PW/cm²). Using our newly designed Reaction Microscope we were able to resolve rich and so far unexplained structures in the electron momentum distributions at intensities well in the tunneling regime. The spectra exhibit pulse length as well as target dependence. [1] N.B. Delone and V.P. Krajnov, Phys. Usp. 41, 469 (1998) [2] R.Moshammer et al, Phys. Rev. Lett. 91, 113002 (2003)