Balmer Emission Yields for Excited Hydrogen Atoms Produced by H⁺, H₂⁺, and H₃⁺ Ions Passing through Thin Carbon Foils

Abstract

Relative emission yields of Balmer lines as functions of the dwell time (t_D=0.97–12.3 fs) in thin carbon foils are measured with beams of H⁺, H₂⁺, and H₃⁺ impinging on thin carbon foils at 0.5 and 0.8 MeV/amu. Large molecular enhancements of emission yields of Balmer lines are observed for H₂⁺ and H₃⁺ beams, where (i) the molecular enhancements for H₂⁺ and H₃⁺ depend on the principal quantum number (n=3–6), (ii) the molecular enhancement for H₃⁺ is higher than that for H₂⁺, and (iii) the molecular enhancements decrease very rapidly in the red regiem (t_D\lesssim2 fs) and slowly in the blue regiem (t_D\gtrsim2 fs) with increasing t_D.