Vacuum ultraviolet absorption spectrum of the van der Waals molecule Xe2. I. Ground state vibrational structure, potential well depth, and shape

The vacuum ultraviolet absorption spectrum of the van der Waals molecule Xe2 has been photographed at high resolution. Ground state vibrational spacings ΔG(v+½) with v = 0–9 have been extracted from the vibronic structure of two electronic transitions. An extrapolation procedure based on an assumed inverse sixth power long-range potential reveals that the ground electronic state of Xe2 supports 25 or 26 bound vibrational levels. Spectroscopic values for the well depth, 195.5 cm−1, and zero-point energy, 10.4 cm−1, are compared to results from recent molecular beam scattering experiments. The shapes of the spectroscopic and scattering potentials are examined by means of Rydberg-Klein-Rees plots of well depth vs well width.