TEMPERATURE LENS AND TEMPERATURE GRATING IN AQUEOUS-SOLUTION

Time profiles of the thermal lens (TL) and transient grating (TG) signals after photoexcitation of several substances in water are observed at various temperatures. These signals are analyzed in terms of the superposition of the temperature lens (Temp.L) and density lens (Dens.L) in the TL case, and of the temperature grating (Temp.G) and density grating (Dens.G) in the TG case. Pure Temp.G and Temp.L signals are observed at similar to 4 degrees C. The fast response of the Temp.L and Temp.G signals can be used to investigate the fast dynamics of the excited state or fast electronic-translational energy transfer processes.