Zero electron kinetic energy and threshold photodetachment spectroscopy of XenI− clusters (n=2–14): Binding, many-body effects, and structures

Abstract

Origins and modeling of many-body exchange effects in van der Waals clustersXe n I Ϫ van der Waals clusters have been investigated by anion zero electron kinetic energy ͑ZEKE͒ and partially discriminated threshold photodetachment ͑PDTP͒ spectroscopy. The experiments yield size-dependent electron affinities ͑EAs͒ and electronic state splittings between the X, I, and II states accessed by photodetachment. Cluster minimum energy structures have been determined by extensive simulated annealing molecular dynamics calculations using Xe-I ͑Ϫ͒ pair potentials from anion ZEKE spectroscopy and various nonadditive terms. The EAs calculated without many-body effects overestimate the experimental EAs by up to 3000 cm Ϫ1 . Repulsive many-body induction in the anion clusters is found to be the dominant nonadditive effect, though the attractive interaction between the iodide charge and the Xe 2 exchange quadrupole is also important. Unique global minimum energy structures for the anion clusters arise from the influence of the many-body terms, yielding, e.g., arrangements with a closed shell of xenon atoms around the iodide anion for the clusters with nϭ12-14. The specific dependence of the EA curve on cluster size allows us to refine the absolute Xe-I bond lengths for the anion, X, I, and II state diatomic potentials to within Ϯ0.05 Å.

Characterization of ArnCl(−) clusters (n=2–15) using zero electron kinetic energy and partially discriminated threshold photodetachment spectroscopy

“…In these investigations the halide ion X Ϫ in the cluster was probed by high resolution anion threshold photodetachment spectroscopy. Species ranging from binary complexes [6][7][8][9] up to large clusters 10,11 have been studied so far. In this work, we extend our experiments to Ar n Cl Ϫ clusters, with the goal of assessing the influence of many-body effects on the structure and energetics of these species.…”

Femtosecond Time-Resolved Photoelectron Spectroscopy

“…Two sets of transitions were studied, corresponding to excitation of [I*( 2 P 1/2 )- -f I( 2 P 3/2 )Xe n + e -); longer lifetimes for the larger clusters implied solvent screening of the delocalized excited electron from the spin-orbit-excited iodine core. The lower [I( 2 P 3/2 )Xe n ] -CTTS state (n ) 6-13), previously suggested to be bound with respect to detachment, 220,221,232,233 exhibited no appreciable decay out to hundreds of picoseconds.…”

Ion pair state emission from I2in rare gas matrices: effects of solvent induced symmetry breaking

“…The I þ and Rg atom interactions are represented by pair potentials based on ab initio calculations which we will elaborate later. The I À -rare gas atom interactions are obtained from the Morse-Morse-switching function-van der Waals (MMSV) potentials which were fit to reproduce Zero Electron Kinetic Energy (ZEKE) spectra [25,26]. The DIM Hamiltonian matrix defined in equation (3) is constructed by summing over the diatomic fragments:…”