Vibrational overtone spectrum of matrix isolated cis, cis-HOONO

Cis, cis-peroxynitrous acid is known to be an intermediate in atmospheric reactions between OH and NO2 as well as HOO and NO. The infrared absorption spectra of matrix-isolated cc-HOONO and cc-DOONO in argon have been observed in the range of 500-8000 cm(-1). Besides the seven fundamental vibrational modes that have been assigned earlier for this molecule [Zhang , J. Chem. Phys. 124, 084305 (2006)], more than 50 of the overtone and combination bands have been observed for cc-HOONO and cc-DOONO. Ab initio CCSD(T)/atomic natural orbital anharmonic force field calculations were used to help guide the assignments. Based on this study of the vibrational overtone transitions of cis, cis-HOONO that go as high as 8000 cm(-1) and the earlier paper on the vibrational fundamentals, we conclude that the CCSD(T)/ANO anharmonic frequencies seem to correct to +/- 35 cm(-1). The success of the theoretically predicted anharmonic frequencies {upsilon} in assigning overtone spectra of HOONO up to 8000 cm(-1) suggests that the CCSD(T)/ANO method is producing a reliable potential energy surface for this reactive molecule. (C) 2007 American Institute of Physics.