Soft-X-Ray Photoabsorption of the No Dimer

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 2b(1), 2a(2), 7b(2), 8a(1) and 8b(2) orbitals. Correlations are found between the experimental integrated oscillator strengths of the two pi* states, at the nitrogen K edge, and the N-localized 2p coefficients of the unoccupied orbitals of the ((1)A(1)) state.