Diffuse Reflectance Spectroscopy DRS in the Visible UV Region

Manghnani, University Press Series in Metallurgy and Material Science, India, 2009, [19]) 

The possibility of transition occurring is determined by spin selection rules ( transitions between different multiplicity terms are prohibited, e.g., singlet triplet) and the Laporte rule ( transition between terms of the same parity, g g and u — u, are prohibited ). It is important to emphasize that a prohibited transition means that the possibility of it occurring was restricted and, therefore, its intensity is reduced. 

Accordingly, the compound spectra formed by transition metals in the solid state (polycrystalline) are formed by a set of low-intensity bands, generally broad and situated at wavelengths between 350 and 1000 nm, attributed to transitions d-d. 

Bands observed in wavelengths that are smaller than 350 nm are very intense and are related to the permitted transitions, called load transfer (LT) bands. These result 

Quantitative measurements are based on Lambert-Beer Law, related to total absorbance of light where the wavelength depends on the absorption coefficient. Standard absorption coefficients are generally used to quantify them. 

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