title: Spectroscopic investigation of Al2N and its anion via negative ion photoelectron spectroscopy.
abstract: Negative ion photoelectron spectroscopy was used to elucidate the electronic and geometric structure of the gaseous Al2N/Al2N- molecules, using photodetachment wavelengths of 416 nm (2.977 eV), 355 nm (3.493 eV), and 266 nm (4.661 eV). Three electronic bands are observed and assigned to the X2Sigma(u)+ <-- X1Sigma(g)+, A2Pi(u) <-- X1Sigma(g)+, and B2Sigma(g)+ <-- X1Sigma(g)+ electronic transitions, with the caveat that one or both excited states may be slightly bent. With the aid of density functional theory calculations and Franck-Condon spectral simulations, we determine the adiabatic electron affinity of Al2N, 2.571 +/- 0.008 eV, along with geometry changes upon photodetachment, vibrational frequencies, and excited-state term energies. Observation of excitation of the odd vibrational levels of the antisymmetric stretch (nu3) suggests a breakdown of the Franck-Condon approximation, caused by the vibronic coupling between the X2Sigma(u)+ and B2Sigma(g)+ electronic states through the nu3 mode.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Meloni
authors.forename: Sean M
authors.initials: SM
authors.lastname: Sheehan
authors.forename: Bradley F
authors.initials: BF
authors.lastname: Parsons
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Neumark