Soft X-ray photoabsorption of the NO dimer

Abstract

X-ray absorption spectra are reported for the first time for the (NO)2 dimer at both the nitrogen and oxygen K edges, the data being obtained from (NO)2 multilayers formed on Ag{111}. The spectra display distinctive features which suggest an electronic structure for excited states of this species. Density functional theory studies of the core-hole excited states provide the basis for spectral assignments at the nitrogen K edge, allowing the identification of the N 1s electron promotion into the 2b1, 2a2, 7b2, 8a1 and 8b2 orbitals. Correlations are found between the experimental integrated oscillator strengths of the two π* states, at the nitrogen K edge, and the N-localized 2p coefficients of the unoccupied orbitals of the (1A1) state.