Refractive Index Curves Research Articles

Study of In 0.53Ga 0.47As/In 0.52Al 0.48As quantum wells on InP by spectroscopic ellipsometry and photoluminescence

inGaAs/InAIAs quantum wells of different well widths were measured by multiple angle of incidence spectroscopic ellipsometry in the wavelength range from 280 to 865 nm. Comparing the experimental data to the calculated results of a theoretical seven-layer model using our refractive index ( n - i k) curves of the materials involved in our structures, we determined all the layer thicknesses, especially the InGaAs well widths. For our samples, in addition, low temperature photoluminescence studies were performed and compared to the results of potential well calculations. A good agreement is obtained between the well widths determined by ellipsometry and photoluminescence, respectively. Thin interface layers, embedding the InGaAs quantum wells are not observed in the wavelength range from 280 to 700 nm.

Ion-neutral collision effect on an Alfvén wave.

This paper reports that ion-neutral collisions in a magnetized plasma cause a drastic change in the dispersion relation of the shear Alfv\'en wave with poloidal mode number m=0, connecting to the branch of the m=+1 compressional Alfv\'en wave at frequencies below the ion-cyclotron frequency. An anomaly of the dispersion then appears on the refractive index curve and a wave packet in this frequency range undergoes strong amplitude damping and profile deformation. It is confirmed that the Kramers-Kronig relation holds for the dielectric function, estimated from both the measured refractive index and damping rate.

Etch mechanism in the low refractive index silicon nitride plasma-enhanced chemical vapor deposition process

In this letter the author reports a generalized mechanism for the plasma-enhanced chemical vapor deposition silicon nitride process which includes simultaneous surface deposition and etching reactions. The etching mechanism is caused by the hydrogen plasma in combination with the high plasma potential. For each deposition versus power or refractive index versus power curve there is a critical point which is determined by the critical power Wcritical. When the power is lower than Wcritical, the process can be explained by conventional deposition mechanisms. When the power is higher than Wcritical, the hydrogen etching mechanisms becomes important. Wcritical depends on other process parameters such as the composition of the feeding stream. Experimental results confirmed the hydrogen etching mechanism, which is selective.

Ray invariants and wave equations for transverse modes in three-dimensional graded-index waveguides

A theory of the second ray invariant is proposed using the theory of plane Frenet curves. Its existence requires that the coordinate dependence of the refractive index in the waveguide cross section should satisfy the regularity condition: curves of equal refractive index differ only by an amount which can be obtained using an isotropic scaling transformation. The theoretical conclusions are illustrated using the example of waveguides having the generalized refractive index distribution n ( r ) = n [ (x/ a) + (y/ b)q].

Computerized automation of optical systems of the analytical ultracentrifuge

Data obtained from experiments by use of an ultracentrifuge, are either given in the form of photos of the refractive index curve, or as registrations of the absorption-profiles, occurring within the cell, which are registered by differential records. Until now only sophisticated and time-consuming data analyses have been applied to measurements of diffusion and sedimentation coefficients by use of photos and records. For improving data handling the optical systems of the ultracentrifuge were computerized by using modern electric equipment. Schlieren photos are handled with a digitizer, scanner registrations by an AD-converter combined with a PC. Various programs are shown for further data acquisition. The specific software and the significant improvements resulting from this procedure, are discussed in the determination of diffusion coefficients.

Vacuum-ultraviolet refractive-index measurement in a negatively dispersive region of xenon

The refractive-index curve of xenon gas was measured for the first time in the negatively dispersive region from about 115 to 117 nm. A technique based on determining the phase-matching conditions for four-wave mixing in a xenon–argon gas mixture was used to make the measurement. The experimentally determined dispersion curve is consistent with previously developed semiempirical calculations.

The shape of the refractive index versus composition curves for hydrogen-bonded liquid mixtures

The dependence of volume fractions ( %V) on the square of the refractive index ( n 2) has been determined for a series of intermolecular hydrogen-bonded systems. An additive linear relationship between %V and n 2 is obtained for weakly hydrogen-bonded solutions of acetone and methanol while mixtures of acetone/water and methanol/water give a parabolic shape for the refractive-index diagrams. Surprisingly, a quasi-linearity (but with singular and turning points not apparent on the refractive-index curves) is found for strongly hydrogen-bonded cases such as 2,2,2-trifluoroethanol(TFE)/water, TFE/acetone, TFE/methanol, 1,1,1,3,3,3-hexafluoro-2-propanol (HFP)/water, HFP/acetone and HPP/methanol. This unexpected observation is explained in terms of the coexistence of various stable hydrogen-bonded species corresponding to different geometrical isomers and polymer complexes in the mixtures. The proposed explanation is confirmed by MENDO/3 molecular orbital calculations.

The effect of substitution of Cu by Zn, Fe and Ag on the optical properties of synthetic tetrahedrite, Cu12Sb4S13

The spectral reflectances of polished specimens of synthetic tetrahedrites were measured in air and oil using normal-incident linearly polarised monochromatic light (λ : 440 nm to 800 nm). The optical constants were calculated using the Fresnel equation. Compositions of the grains studied were determined by electron microprobe. Qualitative observations of absorption were made in polished thin section using transmitted white and infra-red light. Substitution of Cu led to significant changes in the spectral reflectance curves and dispersion curves of the refractive indices of synthetic tetrahedrite. In general the optical properties of the tetrahedrites are those of a semi-conductor with a narrow band gap. The rapid increase in absorption at wavelengths shorter than 500-600 nm corresponds to excitation of electrons across the forbidden band gap to the conduction band. At wavelengths longer than 600 nm, the absorption is low for all the tetrahedrites and the reflectance values follow, in a general way, the refractive index curves. The small differences in the optical properties are due to the type of substituting element and to the varying role of the d electrons in the chemical bonding. The only tetrahedrite with a simple d10 closed shell configuration for all the metal atoms is the composition Cu₁₀¹⁺Zn₂²⁺Sb₄³⁺S₁₃²⁻ which is the only example found to be transmitting in the red and near infra-red.

Optical properties of carbonized preoxidized vitrinites

The optical properties at 546 nm of three vitrinites (daf carbon contents 82.5, 88.0 and 93.1%) have been examined after pre-oxidation for 14 days at 105 °C and carbonization at intervals of 50 °C within the temperature range 300–800 °C. In general, pre-oxidation prior to carbonization produces only relatively small changes in the trends of optical parameters with temperature that were observed for the same vitrinites when carbonized fresh; the properties of the anthracitic vitrinite displayed little modification. Reflectivities of carbonized pre-oxidized vitrinites of bituminous rank are higher than those for the equivalent fresh vitrinites up to 500 °C, supporting the suggestion that oxidation raises aromaticity and consequently the reflectivity. The most noticeable optical difference occurs with the bituminous-rank vitrinites, in the variation with carbonization temperature of their refractive-index curves, which parallel the behaviour of the L c curves of X-ray diffraction studies. In particular, the refractive-index track for the carbonized pre-oxidized vitrinite of coking-coal rank no longer shows the same marked contrast to the refractive-index tracks of vitrinites of higher and lower rank, as it does at temperatures above 600 °C when carbonized fresh. The absorptive indices follow similar trends to the reflectivities for all the chars.

Oxidized vitrinites — their aromaticity, optical properties and possible detection

The behaviour of the dispersion curves of refractive and absorptive index of a vitrinite of high-volatile rank oxidized for different periods of time up to 128 days at 105 °C supports the suggestion that the aromaticity and/or condensation of the vitrinite rise when it is oxidized. Equivocal optical data previously obtained for oxidized vitrinites can probably be explained by the extensive use in earlier microscopical studies of wavelengths in the green region of the visible spectrum. Reflectivity-dispersion data indicate that there is greater possibility of distinguishing oxidized and weathered coals from fresh samples with the microscope by comparing their optical properties in the blue region of the visible spectrum or in the ultra-violet.

Optical properties of carbonized vitrinites

The optical properties have been examined of three vitrinite-rich coals (carbon, daf: 82.5, 88.0 and 93.1%), carbonized at temperature intervals of 25 °C over the greater part of the range 20–950 °C using a heating rate of 2.45 °C/min. The small temperature interval employed has allowed a satisfactory correlation between alterations in the physical state of the carbonized products and fluctuations in the rates of change of their optical properties during carbonization. In general, as temperature rises the variation of all the optical properties reflects the growth and development of organized polycondensed aromatic systems, but in detail reflectivity does not prove as sensitive an indicator of structural changes as do other optical parameters, particularly refractive index. The behaviour of the refractive-index curves of the carbonized vitrinites is governed by changes in the heights of the crystallites forming the aromatic systems. The shape of these curves closely follows the shape of curves produced in independent X-ray diffraction studies giving the heights of crystallites. While all the refractive-index and all the absorptiveindex curves are similar in shape and trend to one another, each of these curves for carbonized coking-coal vitrinite is displaced from the equivalent curves for low-rank bituminous and anthracitic vitrinites. The displacement can be related to the formation of the highly-plastic stage during carbonization of the coking-coal vitrinite, which ultimately yields weakly cross-linked structures with good crystallite orientation, in contrast to the strongly cross-linked structures with lower ordering developed in carbonization of vitrinites of both lower and higher rank.

The propagation of plasma waves near multiples of the electron gyrofrequency

The dispersion relation for electrostatic plasma waves propagating at frequencies near the electron cyclotron harmonics has been evaluated, and used to determine the refractive index curves for varying values of the angle θ between the k vector and the ambient magnetic field B0 in a warm magnetoplasma. It is shown that, under certain circumstances (which are defined), the (@, θ) curves have the characteristic ‘nose’ shapes that are necessary to provide a reflexion in the ambient plasma. Thus, the oblique echo reflexion mechanism (McAfee 1968, 1969a, b), which accounts for the appearance of the resonance signals or ‘spikes’ at the plasma and upper hybrid frequencies fN and fT on topside ionograms, may also be applied to the plasma waves propagating at frequencies near the electron gyro-harmonics. The relatively high damping that occurs for θ # 90° severely restricts the ranges of θ and wave-number k over which the reflexion mechanism applies. The restriction is such that the damping is severe for all values of θ when k is large, and for all values of θ outside a cone of ∽ 2° centred on θ = 90° when k is small.

Spectrum of Volume Relaxation Times in B2O3

Time-index of refraction isotherms were measured for B2O3 glass starting from both a high and a low temperature in the transformation region. The equilibrium index values at each temperature, obtained from both types of approach curve, were identical. As in the case of the density values, the equilibrium refractive index curve as a function of temperature for this glass is not a straight line. The two-relaxation-times (crossover) model was applied to B2O3 glass and fitted the data as well as it did in previous experiments with borosilicate crown and GeO2 glasses. The reverse crossover which was predicted by the model was experimentally confirmed with the B2O3 glass. The spectrum of relaxation times narrowed with decreasing temperature, indicating approach to another region of single relaxation associated with the low-temperature Arrhenius region. The relaxation times for the low-temperature crossover agreed well with those from the high-temperature curves, indicating complete linearity in the experiments. The spectrum of relaxation times was slightly asymmetrical at constant pressure and very asymmetrical at constant volume.

Solubilities and Some Physical Properties of Alkaline Earth Phosphate Glasses

Solubilities and physical properties of phosphate glasses in the systems, alkaline earth oxides-phosphorous pentoxide, were measured. Glass systems concerned in the present study are CaO-P2O5, MgO-P2O5, SrO-P2O5, BaO-P2O5, CaO-MgO-P2O5 and CaO-MgO-SrO-BaO-P2O5. The composition of the glass specimens covered from 0.7 to 1.7 in mole ratio RO/P2O5. The subjects tested in this paper are solubility of P2O5 component in various solvents, chain-length distribution of phosphate ions, mineral composition of the devitrified specimens obtained by heat-treatment, density and refractive index. As the solvents for the solubility test, N/2 hydrochloric acid, 2% citric acid, 10% neutral sodium citrate, 10% sodium hydroxide and 10% ammonium hydroxide etc. were used.The solubility of P2O5 in the acid solvents increased with the increase of mole ratio RO/P2O5, whereas the reverse change was observed in the case of the basic solvents. It was recognized that the solubility by using the neutral solvents gave a maximum value at a composition of RO/P2O5=1. For the sodium hydroxide solvent, MgO-P2O5 glass resulted in a considerably high solubility comparing with the other glasses.The anomalies of some physical properties and solubility in a system MgO-P2O5 glass disappeared by adding other alkaline earth oxide to a original system. For instance CaO-MgO-P2O5 and CaO-MgO-SrO-PaO-P2O5 glasses had no anomalies concerning density and refractive index curves. When the system contained the mixed alkaline earth oxides, glass formation was observed even in high alkaline earth oxide region. The inclusion of RO in the melt of a sample up to 1.7 in mole ratio RO/P2O5 gave the vitrifaction of the specimen. In these mixed alkaline earth glasses, only two kinds of phosphate ions with short size, i.e. ortho and pyro, were detected by paper chromatographic test and their acid solubilities were higher than those of the other phosphate glasses.No change in the size-distribution of the phosphate ions was seen in the process of dissolution of the glasses in the various solvents except for the acid solvents in which the hydrolysis of phosphate ions occured considerably and rapidly. It seems that when these glasses are heat-treated and then devitrified no reaction among the phosphate ions arises and the phosphate ions with the various size in the original glass make the correspondingly crystalline phosphates.

Fully Coupled Hartree-Fock Calculations of the Refractive Index, Dynamic Polarizability, and Verdet Coefficients of Helium, Beryllium, and Neon

Fully coupled Hartree-Fock calculations of the refractive index, dynamic polarizability, and Verdet coefficients of He, Be, Ne, and the corresponding 2-, 4-, and 10-electron isoelectronic series are presented. The time-dependent Hartree-Fock perturbation equations are derived and solved using a variational method, in which the zero-order and the perturbed wave functions are represented by analytical functions containing adjustable parameters which are optimized according to the variational technique. The numerical results for both the refractive index and the Verdet coefficients are fitted to polynomials in even powers of $\frac{1}{\ensuremath{\lambda}}$, where $\ensuremath{\lambda}$ is the wavelength. In this work it is found that the computed refractive indices differ from the corresponding experimental values due to Cuthbertson and Cuthbertson by a very nearly constant amount. That is, if the computed dynamic polarizabilities are adjusted so as to equal the experimental polarizability $\ensuremath{\alpha}$ at zero frequency, then the experimental and theoretical curves of refractive index versus frequency are nearly identical. This adjustment in $\ensuremath{\alpha}$ is around 5% (for He) and 10% (for Ne) of the experimental static polarizabilities. Finally, the calculated transition frequencies are around 2% too large for He, 17% too large for Ne, and 9% too small for Be.

A Theory for the Christiansen Filter

Multiple scattering theory is applied to investigate the filter shape and bandwidth of the Christiansen filter which consists of a suspension of particles in a liquid such that the refractive index vs wavelength curves of the particles and the liquid intersect at a particular wavelength. It is shown that the filter shape is approximately gaussian, and that the fractional bandwidth depends inversely on the rate of change with wavelength of the difference in refractive index of the particles and the liquid and inversely on the square root of the product of the particle concentration, the average particle radius, and the length of the Christiansen cell. Initial agreement with reported experiments is encouraging.

SOME RELATIONSHIPS BETWEEN THE REFRACTIVE INDEX OF FUSED GLASS BEADS AND THE PETROLOGIC AFFINITY OF VOLCANIC ROCK SUITES1

Research Article| January 01, 1966 SOME RELATIONSHIPS BETWEEN THE REFRACTIVE INDEX OF FUSED GLASS BEADS AND THE PETROLOGIC AFFINITY OF VOLCANIC ROCK SUITES1 N KING HUBER; N KING HUBER U. S. GEOLOGICAL SURVEY, 345 MIDDLEFIELD ROAD, MENLO PARK, CALIFORNIA 94025 Search for other works by this author on: GSW Google Scholar C DEAN RINEHART C DEAN RINEHART U. S. GEOLOGICAL SURVEY, 345 MIDDLEFIELD ROAD, MENLO PARK, CALIFORNIA 94025 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1966) 77 (1): 101–110. https://doi.org/10.1130/0016-7606(1966)77[101:SRBTRI]2.0.CO;2 Article history received: 10 Jun 1965 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation N KING HUBER, C DEAN RINEHART; SOME RELATIONSHIPS BETWEEN THE REFRACTIVE INDEX OF FUSED GLASS BEADS AND THE PETROLOGIC AFFINITY OF VOLCANIC ROCK SUITES. GSA Bulletin 1966;; 77 (1): 101–110. doi: https://doi.org/10.1130/0016-7606(1966)77[101:SRBTRI]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract A study of the relationships between the silica content and the refractive index of glass beads fused from volcanic rocks shows that the relationships may vary appreciably from one petrologic suite to another. This confirms the desirability of determining a separate silica refractive-index curve for each suite in order to estimate silica content with maximum accuracy. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not currently have access to this article.

Focusing by an anisotropic plasma interface

When an electromagnetic source confined in a homogeneous, anisotropic plasma half space radiates into the exterior medium, focusing effects may occur wherein the influence of the plane interface bounding the plasma is similar to that of an optical lens. The existence and location of the caustics and focus depends on the various plasma parameters, in particular on the strength and orientation of the externally applied magnetic field, and the refractive index curves for the medium may be used advantageously for the prediction of their properties. After a qualitative discussion pertaining to the general gyrotropic case, a detailed field evaluation for line source and dipole excitation is carried out for the special problem of uniaxial anisotropy, corresponding to an infinitely strong external magnetic field. In this instance, the ray system and the caustics may be described in simple terms and expressions are given for the fields inside or outside the focusing region.

Radiation from a uniaxially anisotropic plasma half space

A line source of magnetic currents is located in a half space with uniaxially anisotropic dielectric constant, with the optic axis inclined at an arbitrary angle to the interface. This two-dimensional, scalar diffraction problem is solved by Fourier integral techniques, and the solution is examined in the asymptotic range of large distance from the source. The radiation field comprises incident, reflected and refracted ray contributions whose properties are determined from a study of the refractive index curves for the medium. In addition, there may exist a lateral wave which is excited by a critically refracted incident ray, and which sheds energy back into the anisotropic medium by refraction. If the medium is a plasma with an externally impressed infinite dc magnetic field, and if the source oscillates below the plasma frequency, there exist shadow regions from which the direct and reflected rays are excluded but which can be penetrated by the lateral waves.

Physical Properties of Binary Systems

Physical properties of two binary systems, isopropyl alcohol-water and isopropyl alcohol-benzene, are determined experimentally. The kinds of physical properties observed are density, refractive index, viscosity and surface tension, whose data are useful for the analysis of binary mixtures. The smoothed data are presented in Table 2 (a). (b) and Figures 1 to 5 (a), (b).Inspection of the Tables and Figures reveals that there are maximums in the viscosity vs. composition curves as well as in refractive index vs. composition curves, for the system isopropyl alcohol-water and that there exists a minimum in the relation between viscosity and composition for the system isopropyl alcohol-benzene. A small addition of isopropyl alcohol is found to reduce the surface tension of water markedlyParachor and molar refractions are calculated, using the data obtained as above, and it is confirmed that these quantities are linearly correlated with molar composition, except for the parachor of the system isopropyl alcohol-water. Molar refraction is also confirmed to be independent of temperature within the range of experiments. Furthermore, some discussions are made on the theoretical relations between surface tension or viscosity and composition.