Photoionization spectroscopy of Ag–rare gas van der Waals complexes

Abstract

Photoionization electronic spectroscopy is reported for the van der Waals complexes Ag–Ar, Ag–Kr, and Ag–Xe. Two band systems are observed for each complex correlating to the 2P1/2←2S and 2P3/2←2S atomic asymptotes. An additional weaker band system correlating to the 2D5/2←2S asymptote is also observed for Ag–Ar and Ag–Kr, but not for Ag–Xe. Extensive vibrational progressions are observed in each of these band systems indicating that there is a large change in bond distance between the ground and excited states. Isotopic analysis confirms that these spectra all have onsets at high vibrational quantum numbers, making it possible to probe the shape of the potentials near the dissociation limits. Hotbands are also observed providing ground state vibrational intervals. Vibrational constants and dissociation energies are obtained for the excited states and dissociation energies are obtained for the ground states of each complex. The excited states correlating to the 2P asymptote are significantly more strongly bound than the ground state for each complex, while the states correlating to 2D are extremely weakly bound with low vibrational frequencies. Dissociation energy trends are compared for the series of complexes and for corresponding spin–orbit states.