Laser dual-wavelength interferometric measurement of the structure and refractive parameters of carbon tetrachloride

The dual-wavelength laser Mach-Zehnder interferometric technique was used for measuring the refractive index and its gradient with temperature for the important laser dye solvent carbon tetrachloride (CTC). The Argon and He-Ne laser, at wavelengths 514.5 nm and 632.8 nm respectively, are used. Applying Maxwell's and Lorentz-Lorenz equations, the structure parameters (optical permittivity, thermal coefficient of permittivity, specific and molar refraction, polarizability, molecular radius, constant dipole moment, relaxation time, impedance, ... etc), of the solvent are calculated at the two wavelengths. The calculations are carried out using the measured data for the refractive index and its gradient with temperature. On the other hand the refractive index gradient with density was determined. Accordingly the optical permittivity, density and molar polarization of CTC at different temperatures were calculated. Using Caushy's equation the refractive index and permittivity as a function of wavelength were deduced. The gradient of refractive index (dn/dT) and hence the gradient of permittivity (d epsilon/dT) versus wavelength are calculated using Murphy-Alpert's equation. In addition the constants A and B of Cauchy equation are plotted as a function of temperature. Accuracy, sensitivity and discussions are treated in details. (C) 1997 Elsevier Science B.V.