Absorption Spectra of Ne2 and HeNe Molecules in the Vacuum-uv Region

Abstract

The absorption spectra of the Ne2 and HeNe molecules have been investigated in the 585–760 Å region with a 6.65 m vacuum spectrograph using the helium continuum as a background source. Twelve discrete band systems are identified in the Ne2 spectrum. The ground state is stable, with a potential depth De=30.2 cm−1, supporting two stable vibrational levels, v=0 and 1, and with B0=0.17 cm−1, giving r0=3.1 Å. A number of existing intermolecular potential calculations agree with these results. State designations, dissociation products, stabilities, and observed transitions are discussed, and analogies are drawn with a previous study of the Ar2 molecule. It is suggested that the observed band systems represent members of Rydberg series converging to some of the Ne2+ states derived from atom combinations Ne (2p6 1S0)+ Ne+ (2p5 2P3/2,1/20). In addition, six band groups are attributed to the HeNe molecule. Here the ground state potential supports only one vibrational level, v=0.