Measurement of Local Temperature for Several Organic Solvents

Measurement of Local Temperature for Several Organic Solvents 

As described in the above section, information on the relation between the temperature and the viscosity of sample solutions is indispensable for determining the temperature from the result of PCS measurement. Examples of q(T) obtained by a conventional method [10] are shown in Pigure 8.7. 

Pigure 8.8a and b, respectively, show fluorescence autocorrelation curves of R6G in ethylene glycol and R123 in water at 294.4 K. The solid lines in these traces are curves analyzed by the nonlinear least square method with Eq. (8.1). Residuals plotted on top of the traces clearly indicate that the experimental results were well reproduced by the 

As was discussed in the previous part, the temperature elevation in the solutions can be ascribed to the absorption of the NIR light by the solvents. In order to quantitatively explain the temperature elevation coefficient, AT/AP, for other solvents, we proposed a simple model that can parametrize the temperature elevation. As easily predicted, the AT/AP value is closely related to the extinction coefficient of light absorption, a, and the thermal conductivity, X. Heat generated at the focal point ofthe NIR beam is proportional to the extinction coefficient, a, and the incident laser power, P, as represented by Eq. (8.5). 

Thermal conduction is assumed to take place from the small spherical heat source with a radius, r. This approximation leads to the one-dimensional heat conduction 

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