Thermal-lens spectrometer for studying thermophysical properties of fullerenes

A thermal-lens spectrometer implementing back-synchronized detection technique with a mode-mismatched optical scheme was constructed. Steady-state and transient signals of thermal-lens spectrometry are used to characterize concentration parameters of aqueous fullerene dispersions (AFDs) at the level of 10$^{-7}$ – 10$^{-5}$ M and to assess thermophysical properties of AFDs. The detection limits of fullerenes in AFDs are 100 nM for C$_{60}$, 80 nM for C$_{70}$ and C$_{78}$ – C$_{88}$, and 60 nM for Y@C$_{82}$, which are 20-fold lower than for spectrophotometry. Suitable precision of measurements of thermal diffusivity and thermal effusivity for AFDs is shown.