Photodissociation spectroscopy of CO3−

Abstract

The photodissociation cross section of gas‐phase CO₃ ⁻ has been measured over the wavelength range from 4579 to 6940 Å, and reveals detailed structure reflecting the vibrational spacings of a predissociating excited electronic state. From an analysis of the structure, we identified three vibrational modes of the excited state having energies of 990, 1470, and 880 cm⁻¹. The bond energy D (CO₂–O⁻) of the ground state CO₃⁻ was determined to be 1.8±0.1 eV, and the electron affinity of CO₃ was found to be 2.9±0.3 eV. By comparison with theoretical calculations, the lowest predissociating state was identified as 1 ²A₁. Observations regarding other excited states of CO₃⁻ are made.