Behavior of positive ions ejected from laser-irradiated CdS

The dynamic behavior of ions ejected by pulsed nitrogen laser irradiation of the single-crystal CdS have been ivestigated with a dynamic mass spectroscopic method. The energetic ions are generated through a process different from that of slow neutrals. The ion produced below 80 mJ/cm2 laser power is created at the surface and accelerated by a Madelung potential, reaching the kinetic energy of 100 eV. At a higher power region, relatively slow cadmium ions showed a Maxwellian velocity distribution suggesting the laser-generated gaseous plasma. Three possible mechanisms for ion formation are presented.