Thermoreflectivity measurements on thin films of white tin have been carried out in the 0.7-4.0-eV photon energy region at room temperature. The technique has allowed a good resolution of the optical structure arising from interband transitions involving the Fermi surface. Contributions to the modulated absorption were located at 0.83, 0.97, and 1.65 eV in good agreement with previous results of static reflectivity measurements.
