Lawrence Berkeley National Laboratory

Slow (v<2E6 m/s), highly charged ions (SHCI), such as Xe44+ and Au69+ deposit 50 to over one hundred keV of potential energy into nanometer scale surface areas within a few femtoseconds when they impinge on solids. Surfaces respond to this intense (~1E13 to 1E14 W/cm2), ultrafast electronic excitation by the emission of electrons, by sputtering and with topographical changes of the surface structure. We recently reported on light emission from silicon surfaces that were exposed to low doses (~1E10 to 1E11 cm-2) of SHCI [1]. Here, light emission was probed in ex situ photoluminescence experiments. In our presentation, we will report on results from studies at the EBIT facility at LBNL [2] where we probe the modification of the electronic properties of different surfaces by the impact of SHCI, and discuss models of the underlying mechanisms. We use ex situ photoluminescence and also began in situ spectroscopy of light emission in the range from 250 to 1200 nm during the impact of SHCIs. Materials studied are silicon with varying dopant levels, SiO2, and scintillator powders. Measurements of electron emission yields complement the light emission studies.