Absorption by Cs₂, Rb₂ and RbCs of radiation at the nine wavelengths of an Ar-ion laser leads to production of molecular and atomic ions via two-photon processes. The authors report absolute probabilities for these processes in Cs₂ and Rb₂ (and relative numbers for RbCs) and discuss the spectral behaviour in the light of spectroscopic information on the potential energy diagrams. For Cs₂, values for the photoionization cross sections of the E state, the intermediate state in the two-step process, are derived.