Atomic hydrogen in intense short laser pulses: a new series of photoelectron peaks from above-threshold ionization

Abstract

The authors have studied atomic hydrogen in intense, short, visible laser pulses (I<or approximately=1.2*1014 W cm-2, tau approximately=0.5 ps, lambda approximately=608 nm). At high intensities (I>6*1013 W cm-2) they observe a new series of higher order above-threshold ionization peaks in the photoelectron energy spectrum. They discuss some tentative explanations. Two models are described in some detail. One relies on ionization saturation, the second one may be named 'parking of atoms as Rydberg wavepackets'.