Molecular enhancement for n-state populations of excited hydrogen atoms produced by H 2+ and H 3+ ions passing through thin carbon foils

Abstract

Relative emission yields of Balmer lines as functions of the dwell time t spd (0.97–54.1 fs) have been measured with beams of 0.2–0.8 MeV/amu H +, H 2 +, and H 3 + ions impinging on thin carbon foils (2–68 μg/cm 2). Large molecular enhancement of emission yields has been observed for H 2 + and H 3 +. Relative populations of n-state hydrogens have been derived from the relative yields of Balmer lines as functions of n (3–5) and t spd (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 t spd = 2 fs, and that the value of molecular enhancement decreases with t spd and is independent of projectile energy at any t spd.