Photothermally induced temperature variations in a low-absorption sample via backside absorption

In order to make the photothermal effect detectable from a sample with low optical absorption, an optically opaque layer must be applied on its surface. A model of optically induced temperature variations for such a structure is derived, with a very thin coating applied on the non-illuminated (back) side of the sample and neglecting heat flux dissipation in the coating. Validation of the model is performed by comparing the obtained results with the results for the corresponding two-layer structure model. The influence of optical absorption on surface temperature variations of both optically transparent and semi-transparent film, whether the film is a good or poor thermal conductor, is analyzed. It is shown that the effects of optical absorption in the coated structure can be observed through variations in the measured temperature, despite the low absorbance of the sample.

Automated summary

To detect the photothermal effect in a sample with low optical absorption, an optically opaque layer needs to be applied on its surface. A model is derived for optically induced temperature variations in this structure, considering a thin coating on the non-illuminated side of the sample and neglecting heat dissipation in the coating. The model is validated by comparing with results from a two-layer structure model. The influence of optical absorption on surface temperature variations in both transparent and semi-transparent films, regardless of their thermal conductivity, is analyzed. It is shown that the effects of optical absorption can be observed through temperature measurements, even for low absorbance samples.