Potentialities of fast ion neutralization at grazing incidence angles From crystal surfaces for development of new generation of uv laser sources

Abstract

The paper considers processes of electron capture by fast ions scattered from metal surfaces at grazing incidence angles. It discuss-es the possibilities of excitation of high atomic levels in neutralization process and laser generation. The Doppler compression effectfor ion beams is shown to be rather essential for laser generation in the ion energy range of several tens keV. It is shown that the four-level laser generation scheme is the preferable one. The values of critical currents for laser generation are evaluated. The experimen-tal setup for ion beam neutralization is observed. The experimental results on nitrogen ion beam neutralization on silicon (001)wafers at grazing incident angles are presented. The dependence of the neutralization coefficient on the grazing incidence angle ismeasured, a good coincidence between peak maximum and Lindhard angles is demonstrated. It is shown that in case of neutraliza-tion without special vacuum surface cleaning the neutralization coefficient makes approximately 30 % for ion energy of 40 keV. Theone-electron resonant neutralization to nitrogen 2P1/2, 2D3/2, 4S3/2 atomic terms is discussed. The mechanism of resonant coher-ent excitation of fast nitrogen atoms in front of a Si (001) surface is observed, the resonant energy being estimated about 70 keV