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ArnCl− clusters have been investigated by anion zero electron kinetic energy (ZEKE) and partially discriminated threshold photodetachment spectroscopy. The experiments yield size-dependent electron affinities (EAs) and electronic state splittings for the X, I, and II states accessed by photodetachment. Cluster minimum energy structures have been determined from calculations based on a “simulated annealing” approach employing our recently presented Ar–Cl(−) pair potentials from anion ZEKE spectroscopy [T. Lenzer, I. Yourshaw, M. R. Furlanetto, G. Reiser, and D. M. Neumark, J. Chem. Phys. 110, 9578 (1999)] and various nonadditive terms. The EAs calculated without many-body effects overestimate the experimental EAs by up to 1500 cm−1. Repulsive many-body induction in the anion clusters is found to be the dominant nonadditive effect. In addition, the attractive interaction between the chloride charge and the Ar2 exchange quadrupole is important. These findings are consistent with our earlier results for XenI−...

Xe n I − clusters ( n ⩽13) have been studied by anion photoelectron (PE) spectroscopy at a photon energy of 4.661 eV and an electron energy resolution of 10 meV. Electron affinities (EA's) as a function of cluster size are extracted and compared to previous PE and tunable laser photodetachment spectra of these species. The EA's found in this study lie between those of the two earlier experiments. These discrepancies are attributed to calibration issues in the earlier PE spectra and the influence of charge-transfer-to-solvent states in the tunable laser experiments.

Zero electron kinetic energy (ZEKE) spectroscopy has been utilized to study the 40 Ar 35 Cl − anion and the X1/2, I3/2 and II1/2 electronic states of neutral ArCl. Well-resolved progressions in the low-frequency vibrations of the anion and the neutral complexes are observed in the ZEKE spectra. From our spectroscopic data we construct model potential functions for the anion and three neutral states. This yields refined values for the neutral state splittings and the first accurate experimental ArCl − anion potential. Absolute uncertainties for R m and e in all potentials are estimated to be ±0.08 A and ±0.6 meV, respectively.

XenI− van der Waals clusters have been investigated by anion zero electron kinetic energy (ZEKE) and partially discriminated threshold photodetachment (PDTP) spectroscopy. The experiments yield size-dependent electron affinities (EAs) 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(−) 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−1. 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 Xe2 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 at...

The XeI− anion and the corresponding neutral X1/2, I3/2, and II1/2 electronic states have been studied by means of zero electron kinetic energy (ZEKE) and photoelectron spectroscopy. The ZEKE spectra show rich and well-resolved progressions in the low-frequency vibrations of the anion and the neutral van der Waals complexes. From our spectroscopic data we construct model potentials for the anion and three neutral states, which are compared to previously obtained potential functions for this system. The intensity of the I3/2←anion transitions relative to the X1/2←anion transitions in the XeI− ZEKE spectrum is considerably lower than expected from a Franck-Condon simulation based on the model potentials. Comparison with the photoelectron spectrum of XeI− indicates this is due to a small s-wave partial cross section for photodetachment to the I3/2 state.

Anion photoelectron spectroscopy is performed on the C(5)H(-) species. Analogous to C(3)H(-) and C(3)D(-), photodetachment transitions are observed from multiple, energetically close-lying isomers of the anion. A linear and a cyclic structure are found to have electron binding energies of 2.421+/-0.019 eV and 2.857+/-0.028 eV, respectively. A cyclic excited state is also found to be 1.136 eV above the linear (2)Pi C(5)H ground state. Based on our assignments of the observed transitions and previous calculations on the energetics of neutral C(5)H isomers, the cyclic (1)A(1) anion state is found to lie 0.163 eV below the (3)A linear anion.