Measurment of thermo-optical properties of water,choloroform and solutions of rhodamine B and 6G using a dual-beam thermal lens technique

A dual-beam transient thermal-lens technique was employed for the determination thermal diffusivity, strength of thermal lensing signal, and varying of signal with laser power of water and choloroform and solutions of rhodamine B and 6G. furthermore, absolute fluorescence quantum-yield of rhodamine solutions in Ethanol, in different concentrations from 10-6 to 10-4 (mol L-1) has been studied. Also, for water and choloroform, varying thermal diffusivity has been considered in different temperature. The experiments were performed in the temperature range between 20 and 80 °C. Used arrangement was dual beam technique with a Q-switched Nd:YAG and a Q-switched Nd:Vanadat laser as pumping sources and He-Ne laser as probe beam. Results show that thermal diffusivty of water include several irregular point about 30,43 and 55( c o ) when its temperature is variable between 20-80 co. Tlsignal strength is larger for choloroform and it for both liquides increas as linear with increasing energy of pump laser,but in several point about 30,43 and 55( c o ) water have irregularity again. These observations may contribute to a better understanding of the physical and chemical properties of water and choloroform. But, in case of rhodamines, Results show that the absolute fluorescence quantum yield of Rhodamine 6G(Rh 6G) is larger rather than Rhodamine B (Rh B) in all concentrations, and with variation of concentration in this interval, that values of Qf of Rh 6G don’t vary significantly. TL strength signal in Rh 6G is larger relative to Rh B.

Keywords:

Absolute fluorescence quantum , choloroform , Rhodamine , thermal diffusivity , thermal lensing , water