Spurious Infrared Absorption Bands

COMMON SPURIOUS INFRARED ABSORPTION BANDS Thomas J. Bruno and Paris D. N. Svoronos... 

ORD techniques do not appear to be useful in the infrared. In the first place, optical rotation is a refraction phenomenon which is not easily studied within absorption bands because of slit-width effects these have given rise to spurious Cotton effects in infrared ORD Secondly, the multiplicity of bands in the middle IR would, at best, give ORD curves of incredible complexity. More telling is the failure of attempts to demonstrate that infrared bands could produce optical rotation in nearby regions of transparency it was found that optical rotation between 4000 and 2000 cm was still dominated by contributions from remote electronic transitions Background rotation of this nature would only make the observation of contributions from infrared bands difficult to discern. 

Christiansen effect A spurious band on the high frequency side of a true absorption band may sometimes be observed when examining the mulls of crystalline materials if the particle size is of the same order of magnitude as the infrared wavelength being used. 

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