Laser pulse-shape independence of the mean energy absorption per electron in multiphoton free-free transitions

Abstract

It is shown that in multiphoton free-free transitions the mean energy absorption per electron is independent of the exact laser energy distribution in space and time. It depends only on the average laser flux, averaged in time over the count time of the electron detector and in space over the electron-target scattering volume. This result is applied in the analysis of recent experimental data.