The geometry of the NO2− anion: ab initio calculations and Franck–Condon analysis

Geometry optimization and harmonic vibrational frequency calculations have been performed on the <f>X˜2A1</f> state of NO2 and <f>X˜1A1</f> state of NO2−. Franck–Condon analyses and spectral simulations were carried out on the NO2(<f>X˜2A1</f>)–NO2−(<f>X˜1A1</f>) photo-detachment process. In addition, the equilibrium geometry parameters, <f>r</f>(NO)=1.248 ± 0.005 A˚ and <f>∠</f>(ONO)=116.8 ± 0.5°, of the <f>X˜1A1</f> state of NO2−, are derived by employing an iterative Franck–Condon analysis procedure in the spectral simulation. Our conclusions regarding the anion geometry suggest a reinterpretation of the results of Woo et al. [Phys. Rev. A 24 (1981) 1380]. [Copyright &y& Elsevier]