Pulsed photothermal spectroscopy with near-field detection

The author investigated the conditions under which pulsed photothermal spectroscopy may be practiced using near-field detection of deformation or temperature. It is shown that there are several ways to do this, with accessible ranges of absorption coefficient differing somewhat. As with previous photoacoustic/photothermal spectroscopies, spectroscopic information may be obtained from 'difficult' samples (opaque, for example). The results also show the advantage of using thin samples for deformation measurements, as relatively large signals are obtained, and saturation is pushed to higher values of the absorption coefficient. Finally, it is noted the techniques described can be utilized in a vacuum environment, in constrast to those requiring a fluid in contact with the sample surface.