PHOTOIONIZATION AND FRAGMENTATION DYNAMICS OF NA3 STUDIED BY ION AND ELECTRON KINETIC-ENERGY ANALYSIS

Two-photon ionization and fragmentation of the metal cluster Na3 via the D (3 2A2) state have been studied with nanosecond pulsed dye lasers in the wavelength range 410-440 nm. We report on a molecular-beam experiment where, for this neutral metal cluster, the photoelectron spectrum and the mass and released kinetic energies of the ionic fragments Na+ and Na2+ as well as their angular distributions have been measured. On the basis of the ion and electron spectra, we conclude that ionization of Na3 and subsequent fragmentation of Na3+ into Na2+ (X) + Na(3s) and Na+ + Na2 (X) occur rather than fragmentation of the excited neutral Na3 cluster with subsequent excited-fragment photoionization.