Ultraviolet Emission Spectrum of Electron-Bombarded Superfluid Helium

Abstract

The emission spectrum of electron-bombarded superfluid helium has been measured as a function of wavelength between 550 and 2500 \AA{}. The spectrum is characterized by a very intense asymmetric band of continuous emission peaking at approximately 800 \AA{} with half-width of roughly 150 \AA{}, along with a series of less intense bands between the wavelengths of 620 and 710 \AA{}. This continuum is due to the radiative dissociation of neutral ${\mathrm{He}}_{2}$ molecules in the reaction $A{^{1}\ensuremath{\Sigma}_{u}}^{+}\ensuremath{\rightarrow}X{^{1}\ensuremath{\Sigma}_{g}}^{+}$.