Refractive Index Deviations Research Articles

The influence of temperature to a refractive index sensor based on a macro-bending tapered plastic optical fiber

Abstract The temperature influence to a refractive index (RI) sensor based on a macro-bending tapered plastic optical fiber (POF) was investigated experimentally. The total temperature dependence loss (TDLtotal) and total temperature dependence RI deviation (TDRtotal) were measured at different temperature (10–60 °C) over an RI range of 1.33–1.41. The temperature dependence RI deviation of the sensor itself was obtained by subtracting the temperature dependence RI of measured liquid from TDRtotal. Therefore, the influence of temperature variation to the sensor was characterized and corrected.

Densities, ultrasonic speeds, refractive indices, excess and partial molar properties of binary mixtures of imidazolium based ionic liquid with pyrrolidin-2-one at temperatures from 298.15 L to 323.15 K

The densities, ρ, speeds of sound, u and refractive indices, nD of binary mixtures of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [Bmim][NTf2] and pyrrolidin-2-one, including those of pure liquids, over the entire composition range were measured at temperatures (298.15, 303.15, 308.15, 313.15, 318.15 and 323.15)K and atmospheric pressure. Using the experimental results, the excess molar volume, VmE, excess isentropic compressibility, κsE, excess molar isentropic compressibility, Ks,mE, excess speed of sound, uE, deviations in refractive index, ΔϕnD, deviations in molar refraction, ΔRM have been calculated. The partial molar volume and compressibility, excess partial molar volume and compressibility over the whole composition range; and the partial molar volume and compressibility, and excess partial molar volume and compressibility, of the components at infinite dilution have also been calculated. The excess properties were correlated by the Redlich–Kister polynomial equations. The variations of these parameters with composition and temperature are discussed in terms of intermolecular interactions prevailing in these mixtures. The VmE values for these mixtures were also calculated by using Prigogine–Flory–Patterson (PFP) theory and the results are compared with experimental findings.

Intermolecular interactions between 2-methyl-2-butanol and petroleum ether at different temperatures: Density, viscosity and refractive index measurements

Experimental data of densities, dynamic viscosities, at 293.15, and 303.15K as well as refractive indices at 293.15, 303.15, 313.15 and 323.15K were measured for the binary systems of 2-methyl-2-butanol and petroleum ether. Computed data from experiment for deviations in viscosity, excess molar volume, excess Gibbs energy of activation of viscous flow and deviation in molar refractive indices were correlated with the Redlich-Kister polynomial equation. Grundberg-Nissan interaction constant (d′), Hind, Frenkel and a modified Kendall-Monroe equation (Eηm) were determined quantitatively. Deviation in viscosity (Δη) were both negative and positive while Excess molar volume (VE), excess Gibbs energy of activation of viscous flow (ΔG*E) and deviation in refractive index (ΔnD) were all positive. These results have been interpreted on the basis of associative and disruptive intermolecular interactions between molecules of 2-methyl-2-butanol and petroleum ether.

Experimental and theoretical excess molar properties of imidazolium based ionic liquids with isomers of butanol

The experimental densities (ρ), speeds of sound (u), and refractive indices (nD) of binary mixtures of 1-octyl-3-methylimidazolium tetrafluoroborate ([C8mim][BF4]) with isomers of butanol (1-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol) were measured at 0.1MPa and at 298.15, 308.15 and 318.15K. Excess molar volumes (VmE), excess molar isentropic compressibilities (Ks,mE), and deviations in refractive index (ΔϕnD) were calculated from the experimental data and were fitted to the Redlich–Kister polynomial equation. The results have been interpreted in terms of interstitial accommodation, ion–dipole interactions, formation of the hydrogen bonds, and structural factors involved in the mixture of ionic liquid and molecular organic solvents. Various mixing rules were used to predict the refractive indices and the data have been compared with the experimental results. In addition, analysis of the present VmE data were done through the Prigogine–Flory–Patterson (PFP) theory and the extended real associated solution (ERAS) model.

Thermodynamic, excess and optical studies on the intermolecular interactions of binary liquid mixtures of imidazolium based ILs

The densities, ρ, speeds of sound, u and refractive indices, nD of binary mixtures of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide {[Bmim][NTf2]} and N-methyl-2-pyrrolidinone (NMP), including those of pure liquids, over the entire composition range were measured at temperatures (298.15, 303.15, 308.15, 313.15, 318.15 and 323.15)K and atmospheric pressure. From the experimental values, the excess molar volumes, VmE, excess isentropic compressibilities, κsE, excess speeds of sound, uE, deviations in refractive index, ΔϕnD and deviations in molar refraction, ΔRM have been calculated. The partial molar volumes, V¯m,1 and V¯m,2 and excess partial molar volumes, V¯m,1E and V¯m,2E over the whole composition range and the partial molar volumes, V¯m,1° and V¯m,2° and excess partial molar volumes, V¯m,1°E and V¯m,2°E of the components at infinite dilution have also been calculated. The variations of these parameters with composition and temperature have been discussed in terms of intermolecular interactions prevailing in these mixtures.

Densities, viscosities and refractive indices of binary mixtures containing methyl ethyl ketone. Friction theory. New UNIFAC-VISCO and ASOG-VISCO parameter determination

In this paper densities, viscosities and refractive indices of four binary mixtures containing methyl ethyl ketone, at atmospheric pressure and in the temperature range from 288.15 K to 333.15 K are reported. From experimental measurements excess molar volumes, viscosity deviations and refractive index deviations are calculated and fitted to the Redlich–Kister equation. For the analysis of molecular interactions present in the mixtures, molar excess Gibbs free energies of activation of viscous flow are also calculated and fitted to the Redlich–Kister polynomial equation. Experimental viscosity data are modeled by friction theory, predictive UNIFAC-VISCO and ASOG-VISCO models and correlative Teja-Rice, Grunberg–Nissan, McAlister, Eyring-UNIQUAC and Eyring-NRTL models. The new CO–CH2O and CO–pyridine interaction parameters are determined for their application in the UNIFAC-VISCO and ASOG-VISCO models.

Volumetric, ultrasonic and spectroscopic studies of molecular interactions in binary mixtures of 1-butyl-3-methylimidazolium hexafluorophosphate with 2-propoxyethanol at temperatures from 298.15 to 323.15 K

The densities, ρ ultrasonic speeds, u and refractive index nD of the binary mixtures of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] with 2-propoxyethanol, including those of pure liquids, have been measured over the entire range of composition at 298.15, 303.15, 308.15, 313.15, 318.15 and 323.15K and atmospheric pressure. The IR spectra of these mixtures have also been recorded at 298.15K. From the experimental data, excess molar volumes, VmE, excess isentropic compressibility, κsE, deviations in ultrasonic speed, Δu, excess molar isentropic compressibility, Ks,mE, and deviations in refractive indices, ΔϕnD were calculated and fitted using the Redlich–Kister equation. The partial molar volumes, V̅m,1 and V̅m,2, partial molar isentropic compressibilities, K̅s,m,1 and K̅s,m,2, excess partial molar volumes, V̅m,1E and V̅m,2E and excess partial molar isentropic compressibilities, K̅s,m,1E and K̅s,m,2E over whole composition range; partial molar volumes, V̅m,1° and V̅m,2°, partial molar isentropic compressibilities, K̅s,m,1° and K̅s,m,2°, excess partial molar volumes, V̅m,1°E and V̅m,2°E and excess partial molar isentropic compressibilities, K̅s,m,1°E and K̅s,m,2°E of the components at infinite dilution have also been calculated. The variations of these parameters with composition and temperature have been discussed in terms of intermolecular interactions prevailing in these mixtures.

Physicochemical properties of a binary mixture of N-methylimidazole and methanol

At atmospheric pressure and over a full molar fraction range, for a binary mixture of x N-methylimidazole + (1-x) methanol, the density, viscosity and refractive index at 308.15K were measured, and the Gibbs energy of activation of viscous flow was calculated. All these properties were, respectively, correlated by a fourth-order polynomial. Based on these properties, the excess molar volume, viscosity deviation and refractive index deviation, and the excess Gibbs energy of activation of viscous flow, were calculated and fitted to a third-order Redlich–Kister polynomial, respectively. The total vapor pressure in the range (303.15–363.15) K was measured and correlated by a cubic equation, as well as the Clausius–Clapeyron equation. The molar enthalpy of vaporization was extrapolated from the Clausius–Clapeyron equation. The compositions of vapor–liquid coexisting phases were measured, and a temperature-composition phase diagram was plotted. A strong attractive molecular interaction between N-methylimidazole and methanol in a liquid mixture is discussed.

Physicochemical properties of binary mixtures of 1,1,3,3-tetramethylguanidine imidazolide ionic liquid with water and alcohols

In this work, densities and viscosities of aqueous solution of 1,1,3,3-tetramethylguanidine imidazolide ([TMG]IM) ionic liquid were measured at temperatures from T=(293.15 to 313.15)K. Volumetric properties including excess molar volumes VE, apparent molar volumes, partial molar volumes, and excess partial molar volumes were calculated from the experimental density. Viscosity deviations Δη, Gibbs energy and excess Gibbs energy of activation for viscous flow were deduced from the viscosity. Moreover, electrical conductivities κ and refractive indices of binary mixtures of [TMG]IM with water and alcohols were determined at 298.15K. The results show that VE values of {[TMG]IM (1)+water (2)} mixture are negative over the whole composition range, while Δη and refractive index deviations ΔnD values exhibit positive deviations, indicating that the hydrogen bonding interaction between [TMG]IM and water is dominant. The absolute values of VE and Δη of the mixture decrease with the increasing temperature. The VE, Δη, and ΔnD can be fitted by the Redlich–Kister equation with satisfactory results. The concentration-dependent κ of the studied systems are fitted to Casteel–Amis equation, showing that the κ values of {[TMG]IM (1)+water (2)} mixture are much higher than those of {[TMG]IM (1)+ethanol (2)} mixture.

Theoretical and experimental study on volumetric and electromagnetic properties of binary systems consisting of 1,2-dichloroethane with benzene and its derivatives at T = (293.15 to 333.15) K

The densities, ρ and refractive index, nD of (1,2-dichloroethane+benzene, +bromobenzene, +chlorobenzene, and +nitrobenzene) have been measured for the whole range of composition at temperature ranging from (293.15 to 333.15)K in T=10K intervals and ambient pressure (81.5kPa), using Anton Paar DMA 4500 oscillating densimeter and Anton Paar Abbemat 500 automatic refractometer. From experimental values, excess molar volumes VmE, partial molar volumes V¯i, apparent molar volumes Vϕi and refractive index deviations ΔnD of binary systems were calculated and VmE and ΔnD were correlated with the Redlich–Kister polynomial. The effect of temperature and benzene ring derivatives on the excess molar volumes and refractive index deviations are discussed in terms of molecular interaction between unlike molecules. The excess molar volumes are positive for 1,2-dichloroethane with benzene and its derivatives and it was found that VmE in the systems increase with increasing temperature. A comparative study has been made of the refractive indices obtained experimentally and those calculated by means of the Lorentz–Lorenz and Gladstone–Dale relations .The perturbed chain statistical associating fluid theory (PC-SAFT) was also applied to correlate and predict the density of mixtures.

Density, Refractive Index, and Sound Velocity for the Binary Mixtures of Tri-n-Butyl Phosphate and n-Butanol between 303.15 K and 323.15 K

Density, ρ, refractive index, nD, and sound velocity, u, have been measured for pure TBP, n-BuOH, and their binary mixtures in the range, 0 ≤ x2 ≤ 1, between (303.15 and 323.15) K at an interval of 5 K. From measured ρ and nD, excess molar volumes, VmE, thermal expansivity, α, excess thermal expansivity, αE, and deviation in refractive index, ΔnD, were calculated. Furthermore, using ρ and u, some derived properties, such as acoustic impedance, z, isentropic compressibility, κs, and their deviations (Δu, Δz, and Δκs), were also calculated. Values of ρ, nD, u, z, and κs were found to correlate with concentration dependent polynomials, whereas the deviations/excess properties were fitted well to Redlich–Kister equations. The variation patterns of the studied properties were discussed with reference to the nature of molecular interactions taking place between the liquids of TBP and n-BuOH.

P28] Revision of assessment of the Pd-Sn binary: replacing of polynomial description of liquid by association model

This work reports thermophysical properties measurements of binary mixtures of N,N-dimethylacetamide with 2-propanol and 2-butanol. Density, ρ, speed of sound, u, refractive index, nD, and kinematic viscosity, ν, were measured over the whole composition range at the temperatures (283.15, 298.15 and 313.15) K and at atmospheric pressure p = 0.1 MPa. Experimental data were used to calculate the following properties: excess molar volume, VE, excess isentropic compressibility, κSE,refractive index deviation, ΔnD, and viscosity deviation, Δη. These properties were correlated with the Redlich-Kister equation. Excess molar volumes were positive for both mixtures. Refractive index deviations were positive for N,N-dimethylacetamide + 2-propanol and negative for N,N-dimethylacetamide + 2-butanol. Excess isentropic compressibilities and viscosity deviations were negative for the two systems. Finally, the results obtained were interpreted based on both structural and energetic effects.

Study of the Physicochemical and Excess Properties of Binary Systems Composed of Ionic Liquids ([Cnmim]Cl, n = 6, 8) and Three Dipolar Aprotic Solvents at T = 288.15–333.15 K

In the present work, physicochemical properties, such as density (ρ), refractive index (nD) and viscosity (η), for six binary systems containing [Cnmim]Cl (Cnmim = 1-alkyl-3-methylimidazolium; n = 6, 8) and three dipolar aprotic solvents [N-methyl-2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone)] were measured at wide composition ranges and temperatures from T = 288.15 to 333.15 K at atmosphere pressure. Moreover, the derived properties, such as excess molar volumes (), apparent molar volumes (Vφ,i), deviations in refractive index (ΔnD), and isobaric thermal expansivity coefficients (αP), were calculated. The Redlich–Kister polynomial equation was fitted to the excess molar volumes and the deviation in refractive index data. The experimental results in this work allow us to discuss the interactions in the mixtures. The physicochemical properties of such systems may be useful for applications of imidazolium-based ionic liquids in the field of chemical engineering.

Effect of the Alkyl Chain Length of the Cation on the Interactions between Water and Ammonium-Based Ionic Liquids: Experimental and COSMO-RS Studies

To improve the understanding of the molecular interactions of water with tetraalkyl ammonium-based ionic liquids (ILs) such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, thermophysical properties such as density (ρ), speed of sound (u), viscosity (η) and refractive index (nD) were measured and a computational study using COSMO-RS was performed. The derived properties such as excess volumes (VE), deviation in isentropic compressibilities (Δκs), deviation in viscosities (Δη), and deviation in refractive indices (ΔnD) under the same experimental conditions for these systems were also estimated. The observed VE and Δκs values are negative over the entire composition of ILs at all investigated temperatures, whereas Δη and ΔnD values are positive under the same experimental conditions. These results reveal that the ammonium-based ILs significantly affect the intermolecular interactions between the solvent molecules. The computati...

Group Refractive Index Measurement of Liquids Using Common-Path Swept Source Optical Coherence Tomography

Department of Biomedical Engineering, University of Texas, Austin, TX 78712, USA(Received: 24 June 2014. Accepted: 5 January 2015)A fiber-optic based common-path swept source optical coherence tomography for a simple andhigh-resolution measurement of the group refractive indices of liquids has been investigated. Thegroup refractive index measurement has been based on the optical length change before and afterinjection of liquid into a transparent glass tube. The gas-cell referenced fiber based common-pathswept source optical coherence tomography instrument was utilized to obtain the group refractiveindices of liquids. The standard deviations of the group refractive indices measured by this methodwere about 1×10

Volumetric properties, viscosities and refractive indices of binary liquid mixtures of tetrafluoroborate-based ionic liquids with methanol at several temperatures

Densities, speeds of sound, viscosities and refractive indices of two binary systems 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4]+methanol and 1-ethyl-3-methylimidazolium tetrafluoroborate [emim][BF4]+methanol, as well as of all pure components, have been measured covering the whole range of compositions at T=(278.15 to 318.15)K and p=101kPa. From this data, excess molar volumes, excess isentropic compressibilities, viscosity deviations and refractive index deviations were calculated and fitted to extended versions of the Redlich–Kister equation. Estimated coefficients of these equations taking into account the dependence on composition and temperature simultaneously were also presented.

A silicon-on-insulator polarization diversity scheme in the mid-infrared.

We propose a silicon-on-insulator (SOI) polarization diversity scheme in the mid-infrared wavelength range. In consideration of absorption loss in silicon dioxide (SiO2), the polarization splitter-rotator (PSR) is designed and optimized with silicon nitride (SiN) upper-cladding and SiO2 lower-cladding. This asymmetry allows the PSR, which consists of mode-conversion tapers and subsequent mode-sorting asymmetric Y-junctions, to be fabricated with a simple one-step etching process. Simulation shows that our PSR has good performance with low mode conversion loss (< 0.25 dB) and low crosstalk (< -18 dB) in a very large wavelength range from 4.0 μm to 4.4 μm. The PSR also exhibits large fabrication tolerance with respect to the size deviations in waveguide width, height and refractive index of the upper-cladding. Additionally, PSR devices based on Y-junctions with SiO2 upper-cladding, and SiN upper- and lower-claddings are designed for potential applications at shorter and longer wavelengths, respectively. These PSR devices could facilitate the development of silicon photonic devices in the mid-infrared.

Thermophysical properties of aqueous solutions of the 1-ethyl-3-methylimidazolium tricyanomethanide ionic liquid

Thermophysical behavior of the binary system [water+1-ethyl-3-methylimidazolium tricyanomethanide ionic liquid (IL)] was thoroughly characterized through systematic measurements of (vapor+liquid) equilibria (water activity aw), mixing enthalpy, density, viscosity, and refractive index. The measurements were performed in the entire composition range and/or specifically in the highly dilute IL region, at T=298.15K or as a function of temperature in the range from (288.15 to 318.15)K. Effective experimental methods minimizing IL sample consumption, using flow arrangements, instrument couplings and high degree of automation were preferably employed. In particular, the aw determination based on the chilled-mirror dew point technique and implemented by an AquaLab 4TE instrument was identified as a generally superior approach to study VLE of (water+IL) systems. Excess thermodynamic properties (Gibbs free energy, enthalpy, heat capacity, and volume) and property deviations from the linear mixing rule (viscosity, refractive index) were evaluated, Padé approximants being used to correlate adequately their complex composition dependences. The extensive aw data were processed by a two-step procedure fitting first the temperature dependence at each isopleth and subsequently the composition dependence at each isotherm. Good estimates could be thus obtained for derivative thermal properties (enthalpy, heat capacity). Alternatively, the water activity and excess enthalpy data were correlated simultaneously by a NRTL-type model, providing their compact, thermodynamically consistent and adequate representation. Despite small absolute values of excess Gibbs free energy (GE), the system is revealed to be highly nonideal, the small GE resulting from close compensation of its large enthalpy and entropy contributions. Large endothermic effects and an enhanced increase of entropy upon mixing found for this system indicate relative weakness of interactions between unlike molecules and a massive structure breakage in the solution. Positive values of excess volume and negative values of viscosity and refractive index deviations found in the major part of the composition range corroborate this general energetic and structural pattern, although the situation appears to be more complicated in the highly dilute IL region, where these properties congruently exhibit a sign inversion.

Experimental measurements and modelling of volumetric properties, refractive index and viscosity of binary systems of ethyl lactate with methyl ethyl ketone, toluene and n-methyl-2-pirrolidone at 288.15–323.15 K and atmospheric pressure. New UNIFAC–VISCO and ASOG–VISCO interaction parameters

Densities, refractive indices and viscosities of three binary systems consisting of ethyl lactate with methyl ethyl ketone (MEK) or toluene or n-methyl-2-pirrolidone (NMP) were measured at eight temperatures (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15 and 323.15) K and atmospheric pressure. From these data, excess molar volumes, deviations in refractive indices and viscosity deviations were calculated and correlated with the Redlich–Kister equation. The obtained results for excess molar volume have been used for analysis of specific molecular interactions between mixture components and the influence of temperature on them. In addition the modeling of VE binary data was performed with the Peng–Robinson–Stryjek–Vera cubic equation of state (PRSV CEOS) coupled with the van der Waals (vdW1) and CEOS/GE mixing rules. The refractive indices of binary mixtures were predicted by various mixing rules and compared with experimental data. The viscosity modeling was done by UNIFAC–VISCO and ASOG–VISCO models, which could be used as predictive if all interaction parameters between functional groups are known, and purely correlative Eyring–UNIQUAC, Eyring–NRTL, Teja–Rice, Grunberg–Nissan and McAlister equations. Due to the high importance of models for viscosity prediction, the experimental values presented in this work, but also the data obtained in previous as well as in ongoing investigations, were used to determine the unknown interaction parameters of several functional groups for their application in the UNIFAC–VISCO and ASOG–VISCO models.

Isothermal (vapour + liquid) equilibrium and thermophysical properties for (1-butyl-3-methylimidazolium iodide + 1-butanol) binary system

Experimental isothermal (vapour+liquid) equilibrium (VLE) data are reported for the binary mixture containing 1-butyl-3-methylimidazolium iodide ([bmim]I)+1-butanol at three temperatures: (353.15, 363.15, and 373.15)K, in the range of 0 to 0.22 liquid mole fraction of [bmim]I. Additionally, refractive index measurements have been performed at three temperatures: (293.15, 298.15 and 308.15)K in the whole composition range. Densities, excess molar volumes, surface tensions and surface tension deviations of the binary mixture were predicted by Lorenz–Lorentz (nD-ρ) mixing rule. Dielectric permittivities and their deviations were evaluated by known equations. (Vapour+liquid) equilibrium data were correlated with Wilson thermodynamic model while refractive index data with the 3-parameters Redlich–Kister equation by means of maximum likelihood method. For the VLE data, the real vapour phase behaviour by virial equation of state was considered. The studied mixture presents S-shaped abatement from the ideality. Refractive index deviations, surface tension deviations and dielectric permittivity deviations are positive, while excess molar volumes are negative at all temperatures and on whole composition range. The VLE data may be used in separation processes design, and the thermophysical properties as key parameters in specific applications.