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 non-vanishing 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.
Revised: March 22, 2001 |
Published: October 9, 2000
Citation
Gutowski M.S., P. Skurski, X. Li, and L.S. Wang. 2000.(MgO)n-(n=1-5) Clusters: Multipole-Bound Anions and Photodetachment Spectroscopy.Physical Review Letters 85, no. 15:3145-3148.PNNL-SA-33568.