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

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P.A. Aleksandrov S.S. Fanchenko S.G. Schemardov

Abstract

Abstract. The paper considers processes of electron capture by fast ions scattered from metal surfaces at grazing incidence angles. It discusses the possibilities of excitation of high atomic levels in neutralization process and laser generation. The Doppler compression effect for 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 experimental 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 is measured, a good coincidence between peak maximum and Lindhard angles is demonstrated. It is shown that in case of neutralization without special vacuum surface cleaning the neutralization coefficient makes approximately 30% for ion energy of 40 keV. The one-electron resonant neutralization to nitrogen 2P1/2, 2D3/2, 4S3/2 atomic terms is discussed. The mechanism of resonant coherent excitation of fast nitrogen atoms in front of a Si (001) surface is observed, the resonant energy being estimated about 70 keV.

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Research Paper