Negative ion photoelectron spectroscopy was used to elucidate the electronic and geometric structure of the gaseous Al 2N/Al 2N - 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 X 2Σ + u ← X 1Σ + g, A 2∏ u ← X 1Σ + g, and B 2Σ + g ← X 1Σ + 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 Al 2N, 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 (ν 3) suggests a breakdown of the Franck-Condon approximation, caused by the vibronic coupling between the X 2Σ + u and B 2Σ + g electronic states through the ν 3 mode.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry