Femtosecond Two-Photon Detachment of Cu^- Studied By PhotoelectronImaging

The wavelength dependence of photoelectron angular distributions (PADs) of two-photon de-tachment of Cu^- has been directly studied by using the photoelectron map imaging. Results show that for the laser field intensity of 6.0×10¹⁰ W/cm², PADs exhibit dramatic change with the external field wavelength. Comparison between the experimental observation and the lowest-order perturbation theory prediction indicates that the pattern of PADs can be explained by the interference of the s and d partial waves in the final state. Relative contri-butions of s and d partial waves in the two-photon detachment at different laser wavelengths are obtained.