Photoionization studies of niobium clusters: Ionization potentials for Nb2–Nb76

摘要: The photoionization efficiency (PIE) spectra for niobium clusters up to Nb76 are measured using laser ionization time‐of‐flight mass spectrometry. Ionization potentials (IPs) assigned from the PIE evolve with same general pattern observed other transition metal (Mn) studied date: a rapid yet nonmonotonic decrease in IP n≂15 followed thereafter by relatively slow and smooth evolution. IPs cluster radius R according predictions of conducting spherical droplet model if limiting (R→∞) is chosen be 0.5 eV lower than bulk polycrystalline work function. Kinetics experiments D2 as coreactant indicate existence two structural forms, one highly reactive, unreactive size range Nb9–Nb12, reactive forms predominant each case. Nb9–Nb12 were recorded sufficient added source selectively titrate these clusters, le...