Infrared E-type band profiles of acetonitrile in condensed media: orientational diffusion and free rotation.
Spectrochim Acta A Mol Biomol Spectrosc
; 56(3): 485-99, 2000 Feb 15.
Article
en En
| MEDLINE
| ID: mdl-10794463
Infrared spectra of liquid acetonitrile (CH3CN) and its solutions in CCl4, CS2, chloroform, dichloromethane, benzene-d6, acetone-d6 and dimethyl sulfoxide-d6 have been studied. E-type bands under investigation (v5 = 3009, v6 = 1448 and v7 = 1041 cm(-1)) were reproduced by the sum of two Cauchy-Gauss components, the narrower (n) and the broader (b) ones. The different temperature behaviour of the components has been found: the integrated intensities of the narrower components, In, decrease with the temperature, while the intensities of the broader ones, Ib, increase. The narrower components of the bands were explained within the framework of the orientational diffusion mechanism. The broader components of v6 and v7 were attributed to the unresolved gas-like vibration-rotational absorption of the molecules. The enthalpy difference between the molecules absorbing via these two different mechanisms was determined from the dependence of ln(In/Ib) upon T(-1) :deltaH0 = 1.26+/-0.15 kcal mol(-1). The broader component of v5 is assumed to be mainly due to interactions of C-H stretching vibrations with single particle and collective motions of molecular dipoles. The narrower components' widths were used for evaluating the spinning diffusion constant of CH3CN. The absorption in C-H stretching region was found to be strongly affected by solvent. These effects were explained within the framework of hydrogen bond formation between the CH3-group of acetonitrile and H-bond acceptor groups of the solvent molecules.
Buscar en Google
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Acetonitrilos
Idioma:
En
Revista:
Spectrochim Acta A Mol Biomol Spectrosc
Asunto de la revista:
BIOLOGIA MOLECULAR
Año:
2000
Tipo del documento:
Article
País de afiliación:
Rusia
Pais de publicación:
Reino Unido