Knowledge Bank

The vacuum ultraviolet absorption spectrum of the van der Waals molecule $Xe2$ has been photographed at high resolution. Ground state vibrational spacings $\Delta Gv+1/2$ with $v=0-9$ have been extracted from the vibronic structure of two transitions. An extrapolation procedure based on an assumed inverse sixth power long-range potential reveals that the ground electronic state of $Xe2$ supports 26 bound vibrational levels. Spectroscopic values for the potential well depth, $195.5cm-1$, and the zero-point energy, $10.4cm-1$, are compared to results from recent molecular beam scattering experiments by means of Rydberg-Klein-Rees plots of well depth versus well width.