Two-photon detachment cross sections for O^-, Cu^-, Ag^- and Au^- at 1064 nm

Absolute two-photon detachment cross sections were determined for irradiation of oxygen, copper, silver and gold negative ions at a wavelength of 1064 nm. A 12 ns Q-switched ND:YAG laser and ion beams of keV energies were employed. Results were derived from measurement of the onset of depletion saturation at higher laser intensity. The respective cross sections in units of 10^-49 cm⁴ s are 0.42 (-0.16, +0.19) (O^-), 1.6 (-0.6, +0.7) (Cu^-), 3.1 (-1.1, +1.3) (Ag^-) and 0.39 (-0.16, +0.19) (Au^-).