Concentration and temperature dependence of the refractive index of ethanol-water mixtures: Influence of intermolecular interactions

• Published in: The European physical journal. E, Soft matter and biological physics Vol. 30; no. 1; pp. 19 - 26
• Main Authors: Jiménez Riobóo, R. J., Philipp, M., Ramos, M. A., Krüger, J. K.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.09.2009; EDP Sciences
• Subjects: Biological and Medical Physics; Biophysics; Chemistry; Complex Fluids and Microfluidics; Complex Systems; Computer Simulation; Ethanol - chemistry; Exact sciences and technology; General and physical chemistry; Models, Chemical; Nanotechnology; Physics; Physics and Astronomy; Polymer Sciences; Refractometry; Regular Article; Soft and Granular Matter; Solution properties; Solutions; Solutions - chemistry; Surfaces and Interfaces; Temperature; Thin Films; Water - chemistry; 78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity); 65.20.Jk Studies of thermodynamic properties of specific liquids; 61.20.Ne Structure of simple liquids; 36.40.-c Atomic and molecular clusters; Water; Intermolecular interaction; Binary mixture; Ethanol; Segregation; Optical properties; Molecular cluster; Refraction index; Alkanol; Alcohol
• ISSN: 1292-8941; 1292-895X
• DOI: 10.1140/epje/i2009-10496-4

The temperature and concentration dependence of the refractive index, n D ( x , T ) , in ethanol-water mixtures agrees with previous data in the ethanol-rich concentration range. The refractive index versus concentration x determined at 20 ° C shows the expected maximum at about 41 mol% water (22 mass% water). The temperature derivative of the refractive index, d n D /d T , shows anomalies at lower water concentrations at about 10 mol% water but no anomaly at 41 mol% water. Both anomalies are related to intermolecular interactions, the one in n D seems to be due to molecular segregation and cluster formation while the origin of the second one in d n D /d T is still not clear.