Excited vibrational states of benzene: High resolution FTIR spectra and analysis of some out-of-plane vibrational fundamentals of C6H5D

We have measured the infrared spectra of the nu(4), nu(10b) and nu(11) fundamental bands of C6H5D in the range 540-830 cm(-1) with an instrumental bandwidth of 0.0024 cm(-1) (unapodized FWHM) using a Bomem DA 002 Interferometric Fourier Transform spectrometer. The rotational analysis for nu(4) yields ground state constants by combining ground state combination differences and published microwave data (M. Oldani and A. Bauder, Chem. Phys. Lett. 108 (1984) 7). Excited state constants for the nu(4) level were obtained up to quartic terms, using Watson's A-reduction Hamiltonian in the IIIr representation, resulting in a band center <(nu)over tilde>(0)(4)=697.593 cm(-1). A partial analysis is presented for the nu(10b) fundamental (<(nu)over tilde>(0)(10b)=778.027 cm(-1)), which appears to be locally perturbed by the nu(16a) + nu(16b) combination band. The very strong nu(11) band is strongly perturbed, most probably by nu(6a) and nu(6b) The results are discussed in relation to comparison with accurate ab initio electronic structure calculations including non Born-Oppenheimer effects as well as potential applications with isotope tracer detection and infrared laser chemistry.