title: (MgO)(-)(n) (n = 1-5) clusters: multipole-bound anions and photodetachment spectroscopy.
abstract: Photoelectron spectra of (MgO)(-)(n) (n = 1-5) reveal a surprising trend: The electron binding energy decreases from n = 1 to 4, and then increases from 4 to 5. Ab initio calculations suggest this pattern is related to the electrostatic interaction between the extra electron and the charge distribution of the neutral cluster. This interaction is significant in MgO (-) and (MgO)-5, for which the lowest nonvanishing multipole moment (LNM) is a dipole; it is smaller for (MgO)-2 and (MgO)-3, for which a quadrupole is the LNM; and it is the smallest for (MgO)-4, for which an octopole is the LNM. The cubic (MgO)-4 is the first octopole-bound anion yet observed experimentally and characterized theoretically.
authors.affiliation: Materials Resources, Pacific Northwest National Laboratory, Richland, Washington 99352, USA. maciej.gutowski@pnl.gov
authors.forename: M
authors.initials: M
authors.lastname: Gutowski
authors.forename: P
authors.initials: P
authors.lastname: Skurski
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: L S
authors.initials: LS
authors.lastname: Wang