Chapter 5 - Design, characterization, and applications of photoacoustic cells and spectrometer

Abstract

Photoacoustic spectroscopy requires a variety of instruments for recording the spectrum to study diverse kinds of samples. The main components of the spectrometer such as light source, light-intensity modulators, photoacoustic cells, detectors, and signal processing systems have been described. Variations in each component of a photoacoustic spectrometer are presented with a special emphasis on the photoacoustic cells along with the miniaturized and portable photoacoustic systems. Different designs of the photoacoustic cell are required to study the solid, liquid, and gaseous samples. Photoacoustic signal enhancement by resonant photoacoustic cells as well as different modes of operation of photoacoustic spectrometers has been discussed to study the opaque, reflecting, and transparent samples. A special case of generation of photoacoustic signal using cw laser without chopping is presented using resonant structure of the photoacoustic cell. The applicability of this system in various fields such as material science, life science, environmental monitoring, food safety, medical imaging, nuclear fusion, as well as in nuclear safety is also discussed.