Molecular enhancement for n-state populations of excited hydrogen atoms produced by H2+ and H3+ ions passing through thin carbon foils

Relative emission yields of Balmer lines as functions of the dwell time tsub(D) (0.97-54.1 fs) have been measured with beams of 0.2-0.8 MeV/amu H+, H2+, and H3+ ions impinging on thin carbon foils (2-68 μg/cm2). Large molecular enhancement of emission yields has been observed for H2+ and H3+. Relative populations of n-state hydrogens have been derived from the relative yields of Balmer lines as functions of n (3-5) and tsub(D) (2-25.5 fs). It was found that the molecular enhancement for n-state populations generally increases with n but becomes approximately independent of n at the shortest tsub(D)=2 fs, and that the value of molecular enhancement decreases with tsub(D) and is independent of projectile energy at any tsub(D). (orig.)