Laser-based measurement of thermophysical properties of diethyl ether and toluene with high accuracy using photo-thermal lens technique

The aim of this paper is to accurately measure the thermophysical properties of diethyl ether and toluene by photo-thermal lens set-up. The thermal lens signal of these liquids was recorded, and results show that the thermal lens formation process in these materials is in the order of milliseconds, while the thermal lens relaxation process is in the order of decaseconds. The thermal diffusivity and thermal conductivity of these solvents were measured at fixed laser energy of 90 mJ and temperature of 293 K. The deviation of the measured values from the literature values was less than 4.2%, which indicates the high accuracy of this optical set-up for measuring thermo-optical properties. Then, thermo-optical coefficient dndT\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left( {{\raise0.7ex\hbox{${{\text{d}}n}$} \!\mathord{\left/ {\vphantom {{{\text{d}}n} {{\text{d}}T}}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{${{\text{d}}T}$}}} \right)$$\end{document} of chloroform, diethyl ether and toluene was measured to be − 6.31 × 10–4, − 7.0 × 10–4, and − 5.5 × 10–4K-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{K}}^{{ - 1}}$$\end{document}, respectively. Also, the refractive index changes with the sample deposited heat dndQ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left( {{\raise0.7ex\hbox{${{\text{d}}n}$} \!\mathord{\left/ {\vphantom {{{\text{d}}n} {{\text{d}}Q}}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{${{\text{d}}Q}$}}} \right)$$\end{document} for these materials were measured to be − 0.407, − 0.436, and − 0.384 mm3J\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\frac{{{\text{mm}}^{3} }}{{\text{J}}}$$\end{document}, respectively.