Photoelectron spectroscopy of the negative cluster ions NO - (N2O)n = 1,2

We have recorded the photoelectron (photodetachment) spectra of the gas-phase negative cluster ions NO^-(N₂ O)₁ and NO^-(N₂ O)₂ using 2.540 eV photons. Both spectra exhibit structured photoelectron spectral patterns which strongly resemble that of free NO^-, but which are shifted to successively lower electron kinetic energies with their individual peaks broadened. Each of these spectra is interpreted in terms of a largely intact NO^-subion which is solvated and stabilized by nitrous oxide. For both NO^-(N₂ O)₁ and NO^-(N₂ O)₂, the ion-solvent dissociation energies for the loss of single N₂ O solvent molecules were determined to be ∼0.2 eV. Electron affinities were also determined and found to increase with cluster size. The localization of the cluster ion's excess negative charge onto its nitric oxide rather than its nitrous oxide subunit is discussed in terms of kinetic factors and a possible barrier between the two forms of the solvated ion.