Fourier-transformed infrared photoacoustic spectroscopy of biological materials.

A new technique for measuring the infrared spectra of solids has been developed. The photoacoustic spectra of hemin, hemoglobin, protoporphyrin IX, and horseradish peroxidase show how this technique can be used to obtain structural information about biological materials which cannot readily be studied by normal transmission infrared spectroscopy. The method requires milligram quantities of material and involves no sample preparation.