Metastable Molecular Ion Emission from Semiconductor Surfaces Under N2 Laser Irradiation

The ion emission from solid surfaces under intense laser irradiation was observed for the first time by F. BRECH and L. CROSS.[1] In spite of numerous investigations of this phenomenon during the past 20 years, the microscopic mechanism of ion emission has not been analyzed well enough, partly due to the lack of time-resolving experiments for identifying bonding/ionic states of emitted particles and for measuring their kinetic energies. Our previous investigation on laser-induced ion-cluster emission from graphite surfaces shows the presence of such unstable ionic states which may be observed only in the time scale of a few micro-seconds.[2]