Electronic spectra of N2 (He)n (n=1,2,3)

Abstract

Ionic clusters of nitrogen and helium have been investigated by recording their electronic spectra in the near UV. Structured bands belonging to 14N2+-He, 14N2 +-(He)2, 14N2+-(He) 3, and 15N2+-He have been measured between 390 and 392 nm close to the N2+ B 2Σu+←X2Σ g+ band origin. Spectra were obtained by exciting mass selected cluster cations with tunable laser radiation and recording the photodissociation cross section as a function of wavelength. The data support the hypothesis that the He - N2+ interaction potential has only a small barrier to internal rotation in both the X and B electronic states. A lower estimate for the dissociation energy of the N2 +-He cluster of 101 cm-1 is inferr..