Electronic properties of dipole-bound (H2O)2−, (D2O)2−, (H2O)2−Arn=1,2,3, and (D2O)2−Arn=1,2,3 using negative ion photoelectron spectroscopy

We present the mass spectral and the photoelectron spectroscopic studies of dipole bound (H2O)2−, (D2O)2−, (H2O)2−Arn=1,2,3, and (D2O)2−Arn=1,2,3. We measured vertical detachment energies (VDEs) of these dipole bound cluster anions and also estimated their adiabatic electron affinities (EAas) to be close to their VDEs, respectively. The photoelectron spectra of (H2O)2−Arn=1,2,3 and (D2O)2−Arn=1,2,3 closely resemble those of (H2O)2− and (D2O)2−, respectively except for a slight successive spectral shift by ∼5 meV to a higher electron binding energy with additional argon atoms, which indicates that the argon atoms hardly perturb the water dimer anion geometry.