Negative ion photoelectron spectroscopy of the AsO− anion

The negative ion photoelectron spectrum of AsO− has been measured, assigned, and analyzed. The adiabatic electron affinity, EAa, was determined directly from the photoelectron spectrum. The dissociation energy of AsO−, D0(AsO−), was computed via an energetic cycle using our measured value of EAa and existing literature values for other necessary quantities. Franck–Condon analysis provided values for the bond length of the AsO− anion, re(AsO−), its vibrational frequency, ωe(AsO−), and its anharmonicity constant, ωeχe(AsO−). The values of the molecular constants which were determined in this work are: EAa(AsO)=1.286±0.008 eV, D0(AsO−)=4.74±0.08eV, re(AsO−)=1.696±0.010 A, ωe(AsO−)=827±40 cm−1, and ωeχe(AsO−)=5.54 cm−1. In addition, we determined the X 3Σ−−a1Δ, ground-to-first excited state splitting in AsO− to be ∼0.54 eV.