ELECTRIC FIELD INFLUENCE ON EMISSION OF CHARACTERISTIC X-RAY FROM Al 2 O 3 TARGETS BOMBARDED BY SLOW Xe + IONS J. C. Rao 1, 2 * , M. Song 2 , K. Mitsuishi 2 , M. Takeguchi 2 , K. Furuya 2 1 Department of Materials Science, Harbin Institute of Technology, Harbin 150001, CHINA 2 High Voltage Electron Microscopy Station, National Institute for Materials Science, 3-13, Sakura, Tsukuba, Ibaraki, 305-0003, JAPAN E-mail: jcrao@hit.edu.cn, RAO.Jiancun@nims.go.jp ABSTRACT Low energy characteristic X-ray emission from Al 2 O 3 monocrystalline specimens is measured under bombardment of 100 keV Xe + ions. The electric field influence on emission of the X-rays of constitute elements in the specimens was investigated. The energy dispersive X-ray spectroscopy (EDS) spectra show that the characteristic X-ray of Al-Kα seems to be depressed by the applied direct current (DC) voltages, while the peak intensity of O-Kα was not notably influenced. The O-Kα peaks were broadened and the total counts increased as a higher DC bias was applied. It is possible that a DC electric field parallel to the target surface may influence the X-ray emission from it under ion bombardment. INTRODUCTION Some insulating samples under ion beam bombardment show important charging effects: a large bremsstrahlung background in the X-ray spectra and enhancement of characteristic X-ray yields of component elements [1-9]. When these insulating samples were bombarded by ion beams, such as protons and alpha particles, they produce a very large bremsstrahlung background in the X-ray spectra. Also, the yields of the X-ray lines of component elements are largely enhanced in comparison to those obtained from the same elemental concentrations in conductive samples or samples simultaneously neutralised by an electron gun. There is compelling evidence connecting the enhancement with the charging up of the samples and some researchers [1-9] attributed the effect to accelerated electrons as the cause of the X-ray yield enhancement. Recently, low energy characteristic X-ray emission was observed, by our group, as a result of bombardment by positive slow ions onto insulating materials. However, the mechanism that leads to the charging of the samples, with consequent buildup of high potentials, is not known. Theory or models concerning the charging and breakdown of insulating samples bombarded by ion 390 Copyright ©JCPDS-International Centre for Diffraction Data 2006 ISSN 1097-0002