Thermal lens investigation of the temperature dependence of the refractive index of aqueous electrolyte solutions

Thermal lens measurements of different aqueous electrolyte solutions have been recorded over the temperature range −10°C–25°C which show major shifts in the temperature of maximum refractive index for each solution. A theoretical investigation of the thermal lens signals with respect to the structure of water reveals that the origin of these observed changes is dependent upon the expansion coefficient and polarisability of the water molecules. In this work, it is shown that the change in the coefficient of expansion is the most significant factor affecting the thermal lens signal intensity in electrolyte solutions.