X-ray production by ion bombardment

2014 The available experimental and theoretical results on ion induced X-rays are briefly surveyed. From experimental data it may be concluded that the mechanism for inner shell excitation by heavy ion-atom collisions is different from that for proton-atom collisions. The latter are described successfully in Plane Wave Born Approximation (PWBA) and in classical Binary Encounter Approximation (BEA), leading to a general agreement with experiment except in the region below about 100 keV, where experimental data begin to fall short of the theoretical approaches. In the case of heavy ion-atom collisions it is supposed that during the collisions resulting from the interpenetration of the atomic shells of the colliding particles a quasimolecule is formed and inner shell electrons are promoted to higher shells leaving inner shell vacancies after the separation of projectile and target atom, which are filled under emission of X-rays or Auger-electrons alternatively. The important distinction of heavy ion-atom as compared to proton-atom collisions such as much higher cross-sections for comparable velocities of the projectiles, apparent energy shift and line broadening in the X-ray spectra, dependence of fluorescence yield on the energy of the impinging ion are discussed in connection with recent results. As ion-induced X-rays offer in certain cases some extreme advantages over electron and photon methods namely high yield, selectivity and in any case high peak-to-background ratios, examples of the use of ion induced X-rays as an analytical tool are given such as elemental tracing and implanted ion detection. REVUE DE PHYSIQUE APPLIQUÉE TOME 11, JANVIER 1976, PAGE