title: Experimental and theoretical study of absorption spectrum of the (CH3)2CO···HF complex. Influence of anharmonic interactions on the frequency and intensity of the C=O and H-F stretching bands.
abstract: IR absorption spectra of mixtures (CH3)2CO/HF and free (CH3)2CO molecules are recorded in the region of 4000-900 cm(-1) with a Bruker IFS-125 HR vacuum Fourier spectrometer at room temperature with a resolution up to 0.02 cm(-1). Spectral characteristics of the 2ν(C=O) overtone band of free acetone are reliably measured. The ν1(HF) and ν(C=O) absorption bands of the (CH3)2CO···HF complex are obtained by subtracting the absorption bands of free HF and acetone and absorption lines of atmospheric water from the experimental spectrum of mixtures. The experimental data are compared with theoretical results obtained from variational solutions of 1D-4D vibrational Schrödinger equations. The anharmonic potential energy and dipole moment surfaces used in the calculations were computed in the MP2/6-311++G(2d,2p) approximation with corrections for the basis set superposition error. Comparison of the data derived from solutions for different combinations of vibrational degrees of freedom shows that taking the inter-mode anharmonic interactions into account has different effects on the transition frequencies and intensities. Particular attention has been given to elucidation of the influence of anharmonic coupling of the H-F and C=O stretches with the low-frequency intermolecular modes on their frequencies and intensities and the strength of resonance between the fundamental H-F and the first overtone C=O transitions.
authors.affiliation: Physical Faculty, St. Petersburg State University, Peterhof, St. Petersburg 198504, Russian Federation.
authors.forename: V P
authors.initials: VP
authors.lastname: Bulychev
authors.forename: E A
authors.initials: EA
authors.lastname: Svishcheva
authors.forename: K G
authors.initials: KG
authors.lastname: Tokhadze
mesh_terms: D000042:Absorption; D000096:Acetone / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D006858:Hydrofluoric Acid / Q000737:chemistry*; D006860:Hydrogen Bonding; D008962:Models, Theoretical; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared; D014732:Vibration; D014867:Water / Q000737:chemistry*
chemical_list: D006845:Hydrocarbons, Fluorinated; D014867:Water; D000096:Acetone; D006858:Hydrofluoric Acid
keywords: Absorption spectra of H-bonded complexes; Anharmonic effects on transition frequencies and intensities; Solution of multidimensional anharmonic vibrational problems