Empirical Determination of the Harmonic Force Constants in Benzene. 4. The Fermi Resonances

Abstract

In this article, we present a continuation of our work on the refinement of the harmonic force constants Fi,k in benzene (in symmetrized Whiffen's coordinates) and on a growing number of higher order (anharmonic) force constants, Fi,j,k and Fi,j,k,l, that are of importance for the benzene isotopomer invariant potential energy surface. The refined set of harmonic and anharmonic force constants improves the agreement between the experimental levels and those calculated theoretically. The emphasis of the present work is on the analysis of the two notable Fermi resonances in benzene (nu8 +nnu1 <=> (n +1)nu1 + nu6, where n = 0, 1, ... m, and nu20 <=> nu8 + nu19 <=> nu1 + nu6 + nu19). For this purpose, we have further extended our fully dimensional, fully symmetrized, and nonperturbative vibrational procedure to the vibrational structure of the benzene isotopic species with D6h symmetry.

The complexes of halothane with benzene: the temperature dependent direction of the complexation shift of the aliphatic C–H stretching

“…The vibrational spectra of the monomers in the vapour phase and in different cryogenic environments are well documented, [23][24][25][26][27] and need not be discussed in detail here. The search for complexes was initiated by studying infrared and Raman spectra of a series of mixtures dissolved in liquid krypton (LKr), containing mole fractions of halothane ranging from 2.8 Â 10 À4 to 1.3 Â 10 À2 and containing benzene(-d 6 ) with mole fractions between 0.9 Â 10 À4 and 5.6 Â 10 À3 .…”