Negative Spectral Interpretation

The spectrum should be interpreted by (a) seeing which absorption bands are absent - negative spectral interpretation - and (b) examining those bands present - positive spectral interpretation. 

With the advances in experimental techniques and theory, MCD spectroscopy became a viable analytical technique and found application in many areas of chemistry (11-17). The distinct spectral forms of A, B, and C terms and the fact that MCD intensity can be positive or negative make an MCD measurement a useful complement to an absorption spectrum. MCD has been found to be rather more useful than MOR as the latter type of spectrum is generally more difficult to interpret (12). 

If two or more transitions overlap, the quantitative interpretation of the MCD spectrum becomes much more difficult and computational curve fitting that requires simple band shapes is needed. Often, the vibrational structure of the MCD spectrum, which will in general be different from the one in the absorption spectrum, will be so pronounced that this assumption is not fulfilled. Although uncommon, there are some cases known where some sections of the vibrational envelope associated with a single electronic transition are positive and some negative. Thus, the appearance of both positive and negative MCD peaks in a spectral region does not necessarily mean that... 

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