ABSTRACT
Photoacoustic spectroscopy (PAS) has emerged as an attractive and powerful technique well suited for sensing applications. The development of high-power radiation sources and more sophisticated electronics, including sensitive microphones and digital lock-in amplifiers, has allowed for significant advances in PAS. Successful applications of PAS in gases and condensed matter have made this a notable technique and it is studied and applied by scientists and engineers in a variety of disciplines. One should always begin discussion on photoacoustic or optoacoustic spectroscopy with a more general discussion on the phenomenon of spectroscopy, namely photothermal spectroscopy. In order to generate acoustic waves in a sample, periodic heating and cooling of the sample is required to produce pressure fluctuations. In comparison with other photothermal techniques, which measure the changes in refractive index or temperature using combinations of probe sources and detectors, PAS measures the pressure wave produced by sample heating.
