The photoacoustic (PA) effect is based on the absorption of infrared radiation by the sample which is heated up and the absorbed heat is transferred into the surrounding gas. Because the FTIR measurement signal is modulated by the interferometer scanner pressure waves are created in the surrounding gas which are detected by a sensitive microphone and converted into an electrical signal. So the sample itself together with the PA cell becomes the detection system. The measurement is non-destructive, the signal is not degraded by the sample morphology and typically no sample preparation is required.
Advanced photoacoustic spectroscopy accessory provides significantly enhanced sensitivity and measurement speed compared to earlier used PA cells. These advantages will cause a renaissance for this very interesting measurement technique and will open the doors for its use in a much wider range of FT-IR application. In particular it will make difficult to prepare samples applicable and demanding research application more easily possible.