Photoelectron spectroscopy of germanium-fluorine binary cluster anions: the HOMO-LUMO gap estimation of Gen clusters

Electronic properties of germanium-fluorine cluster anions (GenFn−; n=1–11, m=1–3) were studied using photoelectron spectroscopy (PES) with a magnetic-bottle type electron spectrometer. Compared between the PES of GenF− and those of the Gen−, it was found that the dope F atom in GenF− deprives each Gen− cluster of excess electron without any serious rearrangement of the Gen framework. The F doping method enables us to estimate the HOMO-LUMO gap of the corresponding neutral Gen clusters (n=4–11). For a diatomic GeF− cluster, furthermore, the vibrational structures could be resolved to determine its vibrational frequency.