A Review on Photoacoustic Spectroscopy

On the basis of photo acoustic effect, photo acoustic spectroscopy is an unusual form of spectroscopy which uses both light and sound and is based on the absorption of electromagnetic radiation by analyte molecule. Photo acoustic effect offers a minimal or no sample preparation, the ability to look at opaque and scattering sample and the capability to perform depth profiling experiment. These features mean that Photo acoustic can be used for on-line monitoring of various gases and also in depth-resolved characterization of materials. The absorbed energy can be measured by detecting pressure fluctuations in the form of sound waves or shock pulses. A photo acoustic spectrum consists of a plot of the intensity of the acoustic signal detected by a microphone or a piezoelectric detector, against the excitation wavelength or another quantity related to the photon energy of the modulated excitation.