ИСТИНА

A thermooptical spectrometer with a linear dynamic signal range corresponding to absorbances of 10–7–10–2 was built. The numerical simulation of heat transfer during the formation of a photothermal signal in the surface-and bulk-absorbing bodies is carried out and the limitations of the approach are shown. An approach to the description of photothermal effects in heterogeneous objects, e.g. in solids with an absorbing surface and nanoparticle solutions, is proposed. Together with the assessment of target substances, it is possible to estimate, with enough accuracy, (1) the thermal diffusivity of the bulk object and (2) the thermal parameters of dispersed particles due to the simultaneous consideration of time-resolved and stationary signals. The first task is relevant for using nanoparticle solutions as heat-conducting materials. Solving the second problem is important for the use of nanoparticles and biological dispersions in medical technologies (laser therapy, theranostics, etc.). This approach has been applied to assess the parameters of aqueous dispersions of fullerenes and nanodiamonds, solutions of proteins of various classes, as well as for some inorganic nanoparticles.