THEORY OF HIGH-FREQUENCY DIFFERENTIAL INTERFEROMETRY - APPLICATION TO THE MEASUREMENT OF INFRARED CIRCULAR AND LINEAR DICHROISM VIA FOURIER-TRANSFORM SPECTROSCOPY

A general method for the direct measurement of differential absorption intensities using a Fourier transform infrared spectrometer is described. The differential intensities must be higher in frequency than the interferogram frequencies and may arise from a periodic variation of the absorption strength of the sample, or by dichroic response of the sample to alternate states of polarization of the infrared beam. Specific expressions are presented for the measurement of circular and linear dichroism. These expressions represent an extension of the Grosjean-Legrand polarization modulation technique to Fourier transform interferometry.