Abstract

Rapid optical field ionization (OFI) for atoms and ions is distinguished using ultra-short laser pulses focussed to peak fields comparable to Coulomb binding values. This nonperturbative field description facilitates understanding of standard sequential ionization and distinguishes the double (or two-electron ejection) ionization process. Following our discovery of double optical field ionization in He⁺² at 614 nm we have extended experiments to include helium, neon and argon at an 800 nm wavelength with varying ellipticity^1,2. We compare double ionization data with predictions from the semi-classical model by Corkum³. New experimental results at 800 nm use 130 femtosecond laser pulses focussed to intensities of order 10¹⁶ W/cm² in the extraction region of a 1 meter time-of-flight spectrometer. Gas pressures ranged from 10^-8 to 10^-5 torr.

© 1994 Optical Society of America