Theory of Diffuse Reflectance DR Spectroscopy

The reflectance depends upon the K/S ratio and not on the absolute values of K and S. The scattering S coefficient is independent from the wavelength over wide spectral ranges and therefore the SKM function reflects the trend of the absorption K coefficient. Moreover, because SKM is a function of a(hv), a plot of (F(RJj against hv can be used to determine f g in powdered semiconductor oxides. 

The SKM theory has some limitations and can be applied only when the following experimental conditions are fulfilled  

Moreover, diffuse reflectance depends on the particle sizes (d). When the particle size decreases, the S coefficient increases since (for d l(xm) and this 

Finally, it must be noted that an interesting consequence of the Kubelka-Munk (KM) equation is that DR spectroscopy has excellent properties for the analysis of trace quantities of absorbing centers dispersed in non-absorbing matrices. As shown in the following equation  

UV Absorption Bands of Insulating Oxides Excitonic Sur ce States 

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