The shape of doppler-broadened spectral lines produced by light atom reflection from metals: II. Experimental — protons on copper

Abstract

During proton bombardment of a copper single crystal the Balmer-β spectral line is observed. This line, at 4861 Å, is considerably broadened, the lineshape has been studied as function of impact energy (10–40 keV) and angle of incidence of the protons with respect to the surface normal. The broadening is attributed to the Doppler effect. Only fast hydrogen atoms can escape from the solid surface in an excited state. The slow moving particles undergo a resonance non-radiative decay process. This is concluded from a comparison between experimental lineshapes and calculated lineshapes according to the theory of part 1 of this two-part paper. Good agreement with the experimental data is obtained when using for the strength of the radiationless de-excitation A' = 1.5 × 10 8 cm/sec. This value appears also to be consistent with the minimum yield in the proton intensity observed under channeling conditions.