MEASUREMENT OF EMISSION-ANGLE-RESOLVED TIME-OF-FLIGHT DISTRIBUTIONS OF SPUTTERED MG+ IONS

We describe an experiment designed to perform emission-angle-resolved time-of-flight (TOF) analysis of sputter-ejected secondary ions as wel l as of laser-postionized sputtered neutral particles. The apparatus i ncludes a rotatable linear TOF mass spectrometer and an electron-cyclo tron-resonance (ECR) plasma ion source for the bombardment of the targ et with a mass-filtered Ar+ ion beam pulse in the keV energy region (i on pulse width about 30 ns). We present emission-angle-resolved time-o f-flight spectra of Mg+ secondary ions sputter-ejected from a polycrys talline Mg-24 target bombarded at 45-degrees incidence. These TOF spec tra also contain additional information on the emission-angle dependen ce of high energy argon projectiles scattered from the target surface.