Normalizing Infrared Photoacoustic Spectra of Solids

Abstract

Abstract Infrared spectra of infrared detectors were measured in order to contribute to our understanding of the normalization of photoacoustic spectra of solids1. Such spectra are usually “source-compensated,” i.e., normalized to account for differences in source emission at different wavelengths, and such compensation or normalizing is done by comparing the single-beam spectrum of the sample to the emission spectrum of the source measured with a detector or, more commonly, to the single-beam spectrum of a carbon material of some sort which is taken to be a flat black absorber. We showed, however, that this assumption was not generally valid because different carbons gave different spectra and, because of the variability of carbons, concluded that it would be better to avoid carbons and use direct measurements of the exciting source to compensate spectra.2 That statement was not further amplified partly because we did not know how absolute direct measurements might be made. These conclusions were support...