Investigation of nonlinear absorption and aggregation in aqueous solutionsof rhodamine B using thermal lens technique

Thermal lensing effect was studied in aqueous solutions of rhodamine B usin g 532 nm, 9 ns pulses from a Nd:YAG laser. A low intensity He-Ne laser beam was used for probing the thermal lens. Results obtained show that it is ap propriate to use this technique for studying nonlinear absorption processes like two photon absorption or excited state absorption and for analyzing d imerization equilibria.