Photoacoustic spectroscopy for gas sensing: Basics, theory, experimental systems, and applications

Abstract

This subchapter starts with a brief history of the photoacoustic (PA) effect which dates back to 1880, followed by a discussion of its theoretical foundations with emphasis on gas sensing. The experimental part includes a presentation of the most important laser sources – preferentially in the mid-infrared for higher detection sensitivitiy – as well as design considerations for PA cells. Various examples of laser-PA systems illustrate the high perfomance characteristics of PA spectroscopy (PAS) in trace gas sensing including multi-component analyses. Applications range from laboratory studies, roadside gas sensing to air-borne measurements and include most recent developments such as 3D printed PA cells, quartz-enhanced (QEPAS), cantilever-enhanced (CEPAS) and intracavity photoacoustic sensing as well as frequency comb PA spectroscopy.