The spectroscopy of the Rydberg and ionic states of the I2-Ar van der Waals complex

A review of the spectroscopy of the Rydberg and ionic states of the I-2-Ar van der Waals complex studied using high resolution laser spectroscopic techniques is presented. Rydberg states of atoms and molecules are unusual because one electron occupies an orbital whose size is large relative to the dimensions of the ionic core. As a result, the bonding character of complexes in which one of the components is excited to a Rydberg state can vary substantially with n and l. In this work, mass-resolved REMPI spectroscopy has been used to study the 6s, 5d and 6d Rydberg states of the I-2-Ar complex and ZEKE (zero kinetic energy) spectroscopy has been used to study the ground state of the ion. In addition to observing large changes in binding energy as n and l increase, evidence is presented for the existence of two stable isomers of I-2-Ar. (C) 1998 Elsevier Science B.V. All rights reserved.