Abstract

We have measured the electron energy distribution from the above-threshold ionization (ATI) of Xe and He atoms at intensities up to 7×10¹⁵ W/cm². This is the first report of ATI spectra of atoms at intensities >2×10¹⁴ W/cm² and, therefore, includes ATI from higher ion stages as well as neutral atoms. Other notable aspects of this work are that these ATI spectra are obtained in the short-pulse regime [1] (negligible ponderomotive acceleration of the nascent electrons) and are obtained with ⁻800 nm radiation. This work is particularly relevant to recent proposed x-ray laser schemes that use photoionization to produce high stages of ionization while leaving the electron distribution relatively cold. [2]

© 1992 Optical Society of America