Vibrational couplings and line shapes of CN stretchings in aqueous KOCN–KSCN binary systems

Infrared spectra in the region of the CN stretching of aqueous KOCN–KSCN binary systems were observed in order to investigate the vibrational coupling between two oscillators. Additivity in infrared intensities was not found by analyzing each band separately. On the contrary, the additivity was largely obtained from analysis through the use of the linear response function including the complex coupling term. The increase of band widths from the pure solutions to the binary systems is explained in terms of damping coupling. These results reveal that the line shape of the binary systems arises from the dynamic coupling process interacting with electromagnetic waves. The mechanical coupling constant is discussed on the basis of the oscillating dipole–dipole interactions. q 2004 Elsevier B.V. All rights reserved.