Photoelectron Imaging and Theoretical Calculations of Bimetallic Clusters: AgCu-, AgCu2-, and Ag2Cu-

Bimetallic clusters of AgCu-, AgCu2-, and Ag2Cu- are investigated by using photoelectron imaging and theoretical calculations. Their photoelectron spectra have been obtained at the wavelength of 355 nm and that of AgCu- is also acquired at 1064 nm. The ground state vertical detachment energies of these three clusters are measured to be 0.96 (1), 2.39 (5), and 2.41 (5) eV. The ground state adiabatic detachment energy of AgCu- is measured to be 0.93 (1) eV. Other spectroscopic constants of AgCu- including its frequency, bond length, and dissociation energy (relative to the products Ag- and Cu) are determined to be 191(15) cm(-1), 2.487(10) angstrom, and 1.39 eV according to its spectrum at 1064 nm. Only upper limits of the ground state adiabatic detachment energies of AgCu2- and Ag2Cu- are estimated by using their spectra at 355 nm. The structures and properties of AgCu-, AgCu2-, Ag2Cu-, and their neutral counterparts are also computed by using a strategy, where the structural optimizations are performed with the PW91PW91 method and the energy calculations are performed with the CCSD (T) method. The calculations are in better agreement with the experiments than most of the previous theoretical work