Normalizing Infrared FT Photoacoustic Spectra of Solids

Photoacoustic spectroscopy (PAS) has only recently emerged as a tool for the investigation of the vibrational spectra of condensed matter and surface adsorbates. Qualitative infrared (IR) photoacoustic spectra of various solid materials have been reported both dispersively 1-5 and in the Fourier transform mode. 6-11 In order to obtain quantitative information from a photoacoustic spectrum (as would be needed to monitor kinetics of surface reactions or for analytical purposes) it is necessary to convert the single beam spectrum into a double beam spectrum by ratioing against the spectral profile of the source radiation as it impinges on the sample. This is called source normalization.