Abstract
We have measured the ion yields for helium ionized by 120 fs, 614 nm laser pulses for intensities near W/. We have found that for these ultrashort pulses the data exhibit a feature which saturates in parallel with the signal indicating that the ionization may proceed nonsequentially. We propose a new mechanism, which can exist only in the tunneling regime, for such nonsequential ionization.
- Received 11 June 1992
DOI:https://doi.org/10.1103/PhysRevLett.69.2642
©1992 American Physical Society