The nitrate radical has been a benchmark system for quantitatively testing ab initio treatments of the Jahn-Teller Effect and nonadiabatic interactions. The spectroscopy of its cation NO3+ may provide an even more challenging system. Ab initio calculations predict that there are four low lying electronic states, three of E symmetry exhibiting the Jahn-Teller Effect that lie 1-2 eV above the ground state. There have been two earlier low resolution experiments using photoionization mass spectrometry and photoelectron spectroscopy. These experiments are consistent with adiabatic calculations indicating that the ground state is a symmetric D3h geometry with an IP= 12.55 eV; however, they give conflicting results on the existence of the excited states. We have performed VUV Threshold PhotoElectron-PhotoIon Coincidence (T-PEPICO) spectroscopy experiments on the radical cation NO3+ using the DESIRS beamline at Synchrotron SOLEIL. The DELICIOUS 3 spectrometer provides photoelectron and photoion imaging coincidence detection. We have observed a high resolution threshold photoelectron spectrum of the stable ground state of NO3+. At slightly higher energies, we find a strong absorption with partially resolved vibronic bands leading exclusively to dissociative ionization. We characterize the spectroscopy of the excited states of NO3+ and the dissociation dynamics leading to the formation of NO2+ + O products and report preliminary calculations.

Photoionization and dissociative ionization of the nitrate radical studied by threshold photoelectron photoion coincidence spectroscopy

248th National Meeting (2014)

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