Thermal diffusion and convection induced in chloroaluminum phthalocyanine–ethanol by a CW He–Ne laser

We study a CW Ne–Ne laser-induced thermal diffusion and convection in a chloroaluminum phthalocyanine–ethanol solution by measuring the transmittance and deflection of the beam normally incident on the sample with the entrance surface parallel and normal to the optical table, respectively. In the former geometry, we find a monotonous increase of transmittance with time and no transmitted beam deflection. We quantitatively simulate the observed transmittance by involving thermal diffusion alone. In the latter geometry, we find a transition of transmittance from ascent to descent with time and a downward transmitted beam deflection. We additionally invoke convection to explain the results.