title: Probing the structure and bonding in Al6N- and Al6N by photoelectron spectroscopy and ab initio calculations.
abstract: The electronic and geometrical structure of a nitrogen-doped Al6- cluster (Al6N-) is investigated using photoelectron spectroscopy and ab initio calculations. Photoelectron spectra of Al6N- have been obtained at three photon energies with seven resolved spectral features. The electron affinity of Al6N has been determined to be 2.58 +/- 0.04 eV. Global minimum structure searches for A6N- and its corresponding neutral form are performed using several theoretical methods. Vertical electron detachment energies, calculated using three different methods for the lowest energy structure and a low-lying isomer, are compared with the experimental data. The ground-state structure of Al6N- is established from the joint experimental and theoretical study to consist of an Al2 dimer bonded to the top of a quasi-planar tetracoordinated N unit, Al4N-, or it can be viewed as a distorted trigonal prism structure with the N atom bonded in one of the prism faces. For neutral Al6N, three low-lying isomers are found to compete for the global minimum, two of which are built from the tetracoordinated Al4N unit. The chemical bonding in Al6N- is discussed on the basis of molecular orbital and natural bond analyses.
authors.affiliation: Utah State University, Department of Chemistry and Biochemistry, Logan, Utah 84322-0300, USA.
authors.forename: Boris B
authors.initials: BB
authors.lastname: Averkiev
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Boldyrev
authors.forename: Xi
authors.initials: X
authors.lastname: Li
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang