Proton Induced X-Ray Emission Analysis: Part I

I. INTRODUCTION

If electrons are removed from the inner shells of atoms the vacancies created are filled by electrons from higher energy levels, giving rise to the emission of radiation. For all but the lightest elements this emission is in the X-ray region of the electromagnetic spectrum. The energy of the emitted X-ray is characteristic of the element emitting the radiation and hence its observation forms a method of identification. The initial inner-shell ionization of the atom can be initiated by bombarding the sample under investigation with photons, electrons, or heavier charged particles, such as alpha particles or protons, giving rise to a variety of microanalytical techniques; X-ray fluorescence analysis, electron microprobe analysis, alpha particle and proton-induced X-ray emission analysis.