Matrix isolation and theoretical studies of ONNO: Assignment of a new combination band and density functional calculations Original Research Article

An investigation of the nitric oxide dimer was conducted utilizing the matrix isolation technique coupled with Fourier transform infrared spectroscopy. A previously unreported absorption in matrices at 3609 cm−1 was observed and has been assigned to the NO dimer. This new absorption has been assigned as a combination band arising from the ν1 and ν5 stretches at 1866 cm−1 and 1776 cm−1, respectively. Density functional theoretical (DFT) calculations were also performed to determine the optimized structures and relative energies of the cis- and the trans-ONNO. The potential energy surface for isomerization via N-N bond torsion was also calculated predicting barriers to isomerization of 30.8 and 8.0 kJ/mol.