Production of n = 3 and n = 4 States of Atomic Hydrogen by Electron Impact on H2

Abstract

Absolute cross sections for the production of $H_{\alpha }\text{(n\hspace{0.17em}=\hspace{0.17em}3\hspace{0.17em}→\hspace{0.17em}2)}$ and $H_{\beta }\text{(n\hspace{0.17em}=\hspace{0.17em}4\hspace{0.17em}→\hspace{0.17em}2)}$ emissions by electron impact on H₂ have been measured in the energy ranges 20–400 eV and 30–400 eV, respectively. Time‐resolved spectra were taken for 50‐, 75‐, and 110‐eV impact in which the s‐state decays could be definitely identified since the decay times agreed with theory. All decays could be fit with a two‐mode decay scheme, the second mode having a lifetime somewhat longer than the d‐state theoretical lifetime. The possibility of Stark mixing of certain states is discussed. Cross sections for the production of atoms in the $\text{3s}$ and $\text{4s}$ states are estimated for 50, 75, and 110 eV. The $\text{3s\hspace{0.17em}→\hspace{0.17em}2p}$ contribution to $H_{\alpha }$ and the $\text{4s\hspace{0.17em}→\hspace{0.17em}2p}$ contribution to $H_{\beta }$ are about 24% and 14%, respectively, at these energies.