Soret feedback in thermal diffusion of suspensions

We have theoretically studied the interaction of a light beam with liquids containing absorbing nanoparticles. We have shown that the Soret effect ensures a feedback that essentially limits heat insertion into the system and the change in its temperature: the temperature rise on the axis of a Gaussian beam is inversely proportional to the Soret constant. Transverse spatial redistribution of the absorbing particles gives a specific thickness dependence of the transparency of the material. These properties not only play an essential role in the study of light interactions with absorbing Solutions, but also can underlie optical methods for measurements of the Soret constant.