Spectroscopy of H-Bonded Systems Theoretical Descriptions

Infrared Spectroscopy of H-Bonded Systems Theoretical Descriptions 

BANDSHAPES OF ISOLATED H-BONDS MODULATION BY INTERMONOMER MODES 

The great width of n/X-H - ), the presence of several submaxima and subminima, clearly show that this band has an anharmonic character. This was first noted by Stepanov (4) and later by Bratos et al. around 1955 (5). Anharmonicity, however, is a concept that needs more precision—as we have already seen, it is by definition present as soon as the development of the vibrational energy on vibrational coordinates requires including terms higher than 

We first suppose Q is the stretching mode Q, which would be appropriate for nearly aU H-bonded systems. In the isolated X-H Y system where the X H distance is q and the X - Y distance Q, with corresponding momenta p = -ih(dldq) and = —ih(dldQ ), the vibrational Hamiltonian may be written as 

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