Heidelberg 2015 – scientific programme
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A: Fachverband Atomphysik
A 20: Interaction with strong or short laser pulses II
A 20.5: Talk
Wednesday, March 25, 2015, 12:15–12:30, C/HSW
Electron-correlation effects in laser-intensity dependent ionization processes observed by transient-absorption spectroscopy of helium atoms — •Andreas Kaldun, Veit Stooss, Christian Ott, Alexander Blättermann, Thomas Ding, Andreas Fischer, and Thomas Pfeifer — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
In our transient-absorption spectroscopy setup we simultaneously observe the line shapes of the singly-excited states of helium (1snp) and the doubly exited states of helium (sp2,n+). Both line series are coherently excited by an attosecond-pulsed extreme-ultraviolet(XUV)field. A strong near-visible (VIS) laser pulse is co-propagating with the XUV. Both pulses overlap spatially and temporally. Scanning the intensity of the VIS laser pulse we observe different ionization thresholds for the uncorrelated (1snp) and correlated (sp2,n+) electronic wave function, respectively. Several different ionization channels (direct photo ionization, autoionization, tunneling, barrier-suppressed ionization) complicate the situation.