Title

The interactions of highly charged ions with surfaces

Date of Completion

January 2000

Keywords

Physics, Condensed Matter|Physics, Atomic

Degree

Ph.D.

Abstract

A highly localized, ultra-fast, intense electronic excitation region results from the release of potential energy stored by slow, highly-charged ions (SHCI) as they impinge upon a surface. These high density excitation regions lead to phase transitions on nanometer length scales at individual SHCI impact sites on silicon surfaces. Photoluminescence (PL) measurements of intrinsic silicon irradiated with highly charged ions (Xe q+ (q > 23) and Auq + (q = 53 and 69)) show a significant increase in the band gap energy (Egap = 1.949 eV) within the irradiated regions. Excitons localized within individual impact sites with a higher band gap energy are responsible for the photoemission. The dispersive behavior of the luminescence with respect to excitation energy shows that the emission proceeds through a multi-phonon scattering process involving at least one dispersionless optical phonon and a single dispersive acoustical phonon. ^