Insight into the binary mixture of ethyl lactate+acetonitrile from density,speed of sound and refractive index measurements

Density, sound velocity and refractive index of ethyl lactate + acetonitrile mixtures were measured at five temperatures from 283.15 to 323.15 K. Excess molar volumes, partial molar volumes, thermal expansion coefficients, isentropic compressibility and molar refraction values were calculated. It is concluded that deviations from ideality in this system should be assigned to the ability of the smaller acetonitrile molecules to occupy free volume space of ethyl lactate.     

Compressibilities of liquid pentadecylcyclohexane and nonadecylcyclohexane from high pressure speed of sound and density measurements

The speed of sound in liquids pentadecylcyclohexane (C₂₁H₄₂) and nonadecylcyclohexane (C₂₅H₅₀) was measured by means of a pulse technique operating at 3 MHz. The measurements were carried out at pressures up to 150 MPa in the temperature range (303.15 to 383.15) K. Additional density measurements were performed up to p=60 MPa in the same range of temperature. From both measurements, the density was evaluated up to p=150 MPa and the isentropic compressibility was determined in the same pressure–temperature domain. The full density data were represented by a Tait-like equation in order to calculate the isothermal compressibility.     

Binary mixtures containing OMIM PF6: density,speed of sound,refractive index and LLE with hexane,heptane and 2-propanol at several temperatures

Experimental densities, speeds of sound and refractive indices of the binary mixtures OMIM PF₆ (1-methyl-3-octylimidazolium hexafluorophosphate) with hexane, heptane, and 2-propanol were determined at T = 293.15, 298.15, and 303.15 K. Excess molar volumes, changes of refractive index on mixing and deviations in isentropic compressibility for the above systems were performed. The liquid–liquid equilibrium data of these binary mixtures were carried out experimentally and the NRTL and UNIQUAC correlative equations were applied.     

Volumetric studies to examine the interactions of imidazolium based ionic liquids with water by means of density and speed of sound measurements

Densities and speeds of sound for aqueous solutions of ionic liquids having 1-butyl-3-methylimidazolium as cation and chloride, bromide, iodide, acetate, tetrafluoroborate, and trifluoromethanesulfonate as anions were accurately measured at various concentrations and temperatures. The data were used in evaluating thermodynamic properties as apparent molar volumes and apparent molar isentropic compressions. Infinite dilution values of these properties were determined using appropriate extrapolation procedures utilizing Debye–Hückel limiting law for electrolyte solutions. Apparent molar isobaric expansions at infinite dilutions were also evaluated from the temperature dependence of apparent molar volumes. The results were interpreted in terms of ionic liquid–water interactions.     

Ionic dissociation of aqueous hydrobromic acid. V. Estimate from refractive index and density measurements

The refractive index of aqueous hydrobromic acid was measured up to 19.6m at 0.25 and 60°C. The density of dilute solutions, 0.0676 to 2.76m, was measured at 25°C to high accuracy. These and supplementary data from the literature yielded apparent molar volumes and refractivities. The latter showed the shallow maximum at low concentrations (less than 1.5m) and the gentle linear decline with increasing concentrations, characteristic of strong electrolytes up to about 8 m. The abrupt decline of the apparent molar refractivity with increasing concentrations is interpreted in terms of the association of hydrobromic acid. The apparent molar volumes can also be interpreted, though only quantitatively, in these terms. The results are related to the previously obtained proton nmr data, concerning the extent of association.     

Water density and polarizability deduced from the refractive index determined by interferometric measurements up to 250 MPa

The refractive index of water is precisely determined in the visible light range as a function of the pressure until 250 MPa by means of a new measurement device that uses a special pipe tee included in an interferometer set. This technique allows revisiting the Bradley-Tait and Sellmeier equations to make them dependent on the wavelength and the pressure, respectively. The Bradley-Tait equation for the pressure dependence of the water refractive index is completed by a wavelength-dependent factor. Also, in the considered pressure and wavelength ranges, it is shown that the Sellmeier coefficients can be straightforwardly linked to the pressure, allowing the determination of the refractive index of water for either any wavelength or pressure. A new simple model allows the determination of the density of water as a function of the measured refractive index. Finally, the polarizability of water as function of pressure and wavelength is calculated by means of the Lorentz-Lorenz equation.     

Density and speed of sound measurements of hexadecane

The density and speed of sound of hexadecane have been measured with two instruments. Both instruments use the vibrating-tube method for measuring density. Ambient pressure (83 kPa) density and speed of sound were measured with a commercial instrument from T = (290.65 to 343.15) K. Adiabatic compressibilities are derived from the density and speed of sound data at ambient pressure. Compressed liquid density was measured in a second instrument and ranged from T = (310 to 470) K with pressures from (1 to 50) MPa. The overall relative expanded uncertainty of the compressed liquid density measurements is 0.10–0.13% (k = 2). The overall relative expanded uncertainty (k = 2.3) of the speed of sound measurements is 0.2% and that of the ambient pressure density measurements is approximately 0.04% (k = 2.3). The ambient pressure and compressed liquid density measurements are correlated within 0.1% with a modified Tait equation.     

Retrieval of the complex refractive index of aerosol droplets from optical tweezers measurements

The cavity enhanced Raman scattering spectrum recorded from an aerosol droplet provides a unique fingerprint of droplet radius and refractive index, assuming that the droplet is homogeneous in composition. Aerosol optical tweezers are used in this study to capture a single droplet and a Raman fingerprint is recorded using the trapping laser as the source for the Raman excitation. We report here the retrieval of the real part of the refractive index with an uncertainty of ± 0.0012 (better than ± 0.11%), simultaneously measuring the size of the micrometre sized liquid droplet with a precision of better than 1 nm (< ± 0.05% error). In addition, the equilibrium size of the droplet is shown to depend on the laser irradiance due to optical absorption, which elevates the droplet temperature above that of the ambient gas phase. Modulation of the illuminating laser power leads to a modulation in droplet size as the temperature elevation is altered. By measuring induced size changes of <1 nm, we show that the imaginary part of the refractive index can be retrieved even when less than 10 × 10(-9) with an accuracy of better than ± 0.5 × 10(-9). The combination of these measurements allows the complex refractive index of a droplet to be retrieved with high accuracy, with the possibility of making extremely sensitive optical absorption measurements on aerosol samples and the testing of frequently used mixing rules for treating aerosol optical properties. More generally, this method provides an extremely sensitive approach for measuring refractive indices, particularly under solute supersaturation conditions that cannot be accessed by simple bulk-phase measurements.     

Density,speed of sound,refractive index and dielectric permittivity of (diethyl carbonate + n -decane) at several temperatures

Density, speed of sound and refractive index values of (diethyl carbonate  + n -decane), were measured at the temperatures (288.15, 293.15, 298.15, and 308.15) K and atmospheric pressure. In addition, dielectric permittivities have been measured for the same mixture and at the same temperatures except at T =  293.15 K. Excess molar volumes, changes of isentropic compressibility on mixing, changes of refractive index on mixing and changes of dielectric permittivity on mixing were computed from the experimental data. The excess molar volumes were compared with predictions from the Nitta–Chao model.     

Relation between density and refractive index of organic compounds

Conclusions It was shown with a high degree of accuracy that the density and refractive index in a homologous series of organic compounds are related by a linear function.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 182–184, January, 1972.     

Relation between refractive index and density of polymer solutions

The relation between the fractive index n and the density ρ of a liquid mixture is formulated as where w_i and Rs_i are the weight fraction and the specific refraction, respectively, of component i. The calculation of the specific refraction of straight-chain polyethylene and polystyrene from data for pure compounds of low molecular weight is discussed. The result is applied to dilute solutions of polystyrene in toluene. The calculated values of (dp/dw)₀ and (d²ρ/dw²)₀ at three different temperatures are compared with measured values. The agreement is satisfactory.     

Comparison of the accuracy of aerosol refractive index measurements from single particle and ensemble techniques

The ability of two techniques, aerosol cavity ring down spectroscopy (A-CRDS) and optical tweezers, to retrieve the refractive index of atmospherically relevant aerosol was compared through analysis of supersaturated sodium nitrate at a range of relative humidities. Accumulation mode particles in the diameter range 300-600 nm were probed using A-CRDS, with optical tweezer measurements performed on coarse mode particles several micrometers in diameter. A correction for doubly charged particles was applied in the A-CRDS measurements. Both techniques were found to retrieve refractive indices in good agreement with previously published results from Tang and Munkelwitz, with a precision of ±0.0012 for the optical tweezers and ±0.02 for the A-CRDS technique. The coarse mode optical tweezer measurements agreed most closely with refractive index predictions made using a mass-weighted linear mixing rule. The uncertainty in the refractive index retrieved by the A-CRDS technique prevented discrimination between predictions using both mass-weighted and volume-weighted linear mixing rules. No efflorescence or kinetic limitations on water transport between the particle and the gas phase were observed at relative humidities down to 14%. The magnitude of the uncertainty in refractive index retrieved using the A-CRDS technique reflects the challenges in determining particle optical properties in the accumulation mode, where the extinction efficiency varies steeply with particle size.     

Density and refractive index measurements in hexaheptyloxytriphenylene, a discotic liquid crystal

Density and refractive index measurements in the discotic liquid crystal hexaheptyloxytriphenylene were performed in the hexagonal columnar Col_ho and isotropic I phases. The temperature dependence of the density ρ(T) for this compound was obtained by combining small angle X-ray data and capillary methods. The ordinary n_o extraordinary n_e and isotropic liquid n_i refractive indices were measured using a modified Abbe refractometer to an accuracy of about 10^-3. To check the consistency of the density and the refractometry experiments we used the Lorentz-Lorenz relation. An anomaly in the empirical relationship at the Col_ho-I phase transition, which holds for many uniaxial liquid crystals, was detected. A discrepancy between low birefringence Δn∼0.109 and a relatively high local electric field anisotropy for hexaheptyloxytriphenylene is discussed.     

Density and refractive index measurements in hexaheptyloxytriphenylene,a discotic liquid crystal

Density and refractive index measurements in the discotic liquid crystal hexaheptyloxytriphenylene were performed in the hexagonal columnar Col_ho and isotropic I phases. The temperature dependence of the density ρ(T) for this compound was obtained by combining small angle X-ray data and capillary methods. The ordinary n _o extraordinary n _e and isotropic liquid n _i refractive indices were measured using a modified Abbe refractometer to an accuracy of about 10^?3. To check the consistency of the density and the refractometry experiments we used the Lorentz–Lorenz relation. An anomaly in the empirical relationship at the Col_ho–I phase transition, which holds for many uniaxial liquid crystals, was detected. A discrepancy between low birefringence Δn～0.109 and a relatively high local electric field anisotropy for hexaheptyloxytriphenylene is discussed.     

Cellulose derivative/barium titanate composites with high refractive index,conductivity and energy density

Cellulose - This work deals with hydroxypropyl cellulose (HPC)/barium titanate (BT) composites, having small levels of perovskite-like BT loading, i.e. 0.5–2% and being designed for electric...     

Influence of temperature on the micellization of sodium dodecylsulfate in water from speed of sound measurements

Speed of sound measurements for aqueous solutions of sodium dodecylsulfate (NaDS) have been carried out from 20 to 45°C at intervals of 5°C. The critical micellar concentrations (cmc) were determined and their change with temperature is discussed. A second change in the speed of sound has been found between 15 to 20mM for temperatures above 20°C. Values for G _m ^o , H _m ^o and S _m ^o for the micellization process have been determined and compared with data previously obtained from other experimental properties. These results confirm that the micellization process of NaDS in water is mainly entropically driven.     

Anomalous density and refractive index variation of a nematic liquid crystal

This paper reports the results of the measurement of refractive indices and densities of p-ethoxyphenyl trans-4-butyl cyclohexane carboxylate at different temperatures. The molecular polarizabilities have been calculated from refractive indices using Vuks' formula and orientational order parameters are determined from the polarizability values. The order parameter values have been compared with those obtained from Maier-Saupe theory. The compound shows anomalous behaviour regarding variation of density, ordinary refractive index and order parameter values with temperature. This is consistent with our previous X-ray study of this compound. The possible reason for this peculiar behaviour has been discussed.