Knowledge Bank

The CIRCLE attenuated total reflection FTIR accessory is used to measure infrared optical and dielectric constants and the infrared conductivity, with a Bruker IFS 113V FTIR spectrometer. The method, calculations, and programs (written for the Bruker Aspect 2000 computer in Pascal with some assembly language routines) will be described. For condensed phases it is the infrared conductivity, not the Beer-Lambert coefficient, that provides the simple measure of absorption, i.e. of $(\partial \mu /\partial Q)2$, that the Beer-Lambert coefficient provides for a gas. The infrared optical and dielectric constants and the infrared conductivity of liquid aliphatic alcohols will be presented, including the evidence that the magnitude of the dipole moment change during an O-H stretching vibration is independent of the alcohol within $\pm 2$ for liquid $CH3OH,C2H5OH,n-C3H7OH,n-C4H9OH$ and $n-C7H15OH$.