Photoacoustic Spectroscopy

Abstract

Photoacoustic spectroscopy (PAS) is a technique to measure photoabsorption by measuring the intensity of sound generated by the photoabsorption of chopped or modulated, i.e., continual light by a sample, but not by measuring the intensity of light reduced by the sample photoabsorption as is in the ordinary photoabsorption spectroscopy. Therefore, PAS is one of the best techniques or even only sole one to measure photoabsorption by solid materials such as particulate photocatalysts. Another feature of PAS is that photoirradiation of continuous light, even at the same wavelength of continual light for PA signal detection, does not give any influence on the photoabsorption measurement. This enabled to develop double-beam photoacoustic spectroscopy (DB-PAS), in which two beams, wavelength-scanned modulated light and continuous light which induces photoinduced reaction or change of solid materials, are irradiated to a sample and photoinduced change in photoabsorption of a system. In reversed double-beam photoacoustic spectroscopy (RDB-PAS), wavelength-scanned continuous light and monochromatic continual light are irradiated to follow the change in photoabsorption at the wavelength of continual light induced by wavelength dependent photoinduced reaction.