Differential absorption mueller matrix spectroscopy and the infrared detection of crystalline organics

The complete 16-element Mueller matrices for backscattering from amino acids, sugars, and other enantiomorphic compounds pressed into wafer form were measured at infrared wavelengths. For each compound a pair of CO(2) laser lines was selected from the 9.1-11.6-mum region such that one line excited an absorption band in the compound, whereas the other did not. It was observed that at least some of the matrix elements differed significantly depending on which of the two wavelengths was used in the measurement. We propose that a neural network pattern recognition system can be trained to detect the presence of specific compounds based on multiwavelength backscatter Mueller matrix measurements.