The emission of radiation near 600 Å by helium

Abstract

Free-free radiative emission by a pair of atoms is discussed, and explicit formulae are derived for the free-free spontaneous emission rate, which include contributions from quasi-bound resonating states. The theory is applied to the interpretation of helium emission near 600 Å, and it is suggested that the 600 Å emission bands arise primarily from transitions from quasibound resonating vibrational levels of the A ¹Σ_u ⁺ state of He₂. Analysis of the emission data leads to a dissociation energy of 2·50 eV for the A ¹Σ_u ⁺ state.