Studies of the interaction of slow very highly charged ions with solid surfaces using the LLNL EBIT facility

Abstract

A summary of the present status of the LLNL EBIT based research program on highly charged ion-solid surface interaction is presented. New results for coincidence measurements of K α−K β X-ray emission for Fe 26+ incident on Al, using two Ge detectors are presented. It is shown that excellent resolution of the satellite and hypersatellite lines are achieved, in excess of what is possible with single Ge detector measurements. Recent results from ongoing investigations on electron emission, sputtered ion and energy loss phenomena are presented. Results from charge-state analysis of grazing incidence specular scattering of highly charged ions off atomically flat surfaces of gold, carbon and mica indicate that the incident ion essentially reaches ground state of its electronic distribution within the ion-surface interaction time of ∼ 100 fs. Atomic force microscopy is used to investigate the formation of a new type of ion induced surface defect, peculiar to highly charged ion-surface interactions. A linear correlation, between the defect volume and the incident ion charge, supports a mechanism of defect formation due to potential energy induced electron emission and subsequent collective displacement due to local charge imbalance.