Multiphoton ionization of V, Cr, Y, La, and Ir through 0.5-ps ultraviolet laser pulses

The two-photon ionization of the metal atoms V, Cr, Y, La, and Ir sputtered by an Ar-ion gun from solid targets has been investigated using linearly p olarized laser pulses of 500-fs duration and 248.6-nm (KrF) wavelength in c ombination with mass spectroscopy that is free of volume effects. A near-re sonant ionization process has to be attributed to all five atoms. By fittin g analytical solutions of a rate equation model describing the temporal evo lution of the ionization process, we can determine absolute values of the o ne-photon cross sections and saturation intensities. [S1050-2947(99)04810-6 ].