PNNL

Abstract

We report a photoelectron spectroscopy and computational study of two simple boron oxide species: BO– and BO2–. Vibrationally-resolved photoelectron spectra are obtained at several photon energies (355, 266, 193, and 157 nm) for the 10B isotopomers, 10BO– and 10BO2–. In the spectra of 10BO–, we observe transitions to the 2 sigma + ground state and the 2 pi excited state of 10BO at an excitation energy of 2.96 eV. The electron affinity of 10BO is measured to be 2.510 plus/minus 0.015 eV. The vibrational frequencies of the ground states of 10BO– and 10BO, and the 2 pi excited state are measured to be 1,725 plus/minus 40, 1,935 30, and 1,320 plus/minus 40 cm-1, respectively. For 10BO2–, we observe transitions to the 2 pi g ground state and two excited states of 10BO2, 2 pi u and 2 signa u+, at excitation energies of 2.26 and 3.04 eV, respectively. The electron affinity of 10BO2 is measured to be 4.46 plus/minus 0.03 eV and the symmetrical stretching vibrational frequency of the 2 pi u excited state of 10BO2 is measured to be 980 plus/minus 30 cm-1. Both density functional and ab initio calculations are performed to elucidate the electronic structure and chemical bonding of the two boron oxide molecules. Comparisons with the isoelectronic AlO– and AlO2– species and the closely related molecules CO, N2, CN–, and CO2 are also discussed.