Anion photoelectron spectroscopy of BN−

Photoelectron spectra of the BN− anion at 266 nm and 355 nm are reported. We observe transitions to the ground and three lowest excited states of BN. The electron affinity of BN (X 3Π) is 3.160±0.005 eV. Spectroscopic constants for the anion (X 2Σ+) are re=1.284±0.005 Å, ωe=1660±40 cm−1 and ωeχe=12±4 cm−1. Term energies T0 for the excited states of BN are 0.031±0.004 eV (a 1Σ+), 0.468±0.004 eV (b 1Π) and 1.221±0.006 eV (A 3Σ+).