Evolution of electronic structure as a function of size in gallium phosphide semiconductor clusters

Anion photoelectron spectra have been taken of GaxPy− clusters at a photodetachment wavelength of 266 nm (4.657 eV). Clusters of varying stoichiometry with up to 18 atoms have been investigated. We obtain electron affinities and vertical detachment energies to the ground and low-lying excited states of the neutral clusters. Photoelectron spectra of clusters with 3–5 atoms are compared to previously reported ab initio calculations. Trends in the electron affinities and excitation energies for the larger clusters are discussed.