Photothermal spectroscopy and Its application

The nonradiative processes associated with the absorption of electromagnetic radiation result in the heating of the material (solids, liquids, or gases) under investigation. Typical values of the temperature rise are 10-5°C. This temperature rise is what is exploited to measure very small optical absorption coefficients (αl ~ 10−8) and to determine thermal and electronic transport properties of matter. Over the past few years we have developed two purely optical approaches for performing photo-thermal spectroscopy: photothermal deflection1 and photothermal displacement.2