Refractive index, calculation

The factor f reduces the oscillation amplitude symmetrically about R - R0, facilitating straightforward calculation of polymer refractive index from quantities measured directly from the waveform (3,). When r12 is not small, as in the plasma etching of thin polymer films, the first order power series approximation is inadequate. For example, for a plasma/poly(methyl-methacrylate)/silicon system, r12 = -0.196 and r23 = -0.442. The waveform for a uniformly etching film is no longer purely sinusoidal in time but contains other harmonic components. In addition, amplitude reduction through the f factor does not preserve the vertical median R0 making the film refractive index calculation non-trivial. 

The importance of specific volume or density in determining refractive index is apparent in Equations 1 and 2, which are used in calculating refractive index and molar refraction. This inverse relationship between specific volume and refractive index is illustrated in Table n (cf. columns 2 and 4). The necessity of obtaining an accurate value for the specific volume of a protein in order to obtain agreement between its refractive index calculated from the amino acid composition and the determined value can be illustrated in the case of ribonu-... 

Varying the angle of incidence, a mode spectrum can be obtained and the effective refractive indexes calculated for both TE and TM polarizations. Adequate software allows real-time monitoring of any surface process, providing information on refractive index, thickness of the adsorbed molecular layer and adsorbed mass per unit surface. Measuring time is about 2 min per spectrum with an accuracy of 0.005° and a surface density detection limit around 1 pg/mm, which is enough for measuring small molecules. 

The refractive index of the ethane/propane mixture, needed for calculation of the scattering vector, was determined from experimental density measurements and an empirical Lorentz-Lorenz relationship (12). Incorporating the errors from the viscosity and refractive index calculations into the Stokes-Einstein relation results in a maximum error in the hydrodynamic radius of approximately 5%. 

M. Harris, M. Bowden, G. Hayden and H. A. Macleod, Refractive index calculations for thin film with columnar structure . Paper presented at the Institute of Physics Meeting on Developments in Optical Thin Film Coatings, Imperial College, London, March 27,... 

Figure 4. Real (n) and Inaglnary (k) Parts of the Coiq>lex Refractive Index Calculated From Reflectance Measurements for Blsphenol A Polycarbonate Film...

The usual practice for the process operator is to determine the refractive index of a sample of the oil during hydrogenation, since this can be done in a few minutes, on site. It correlates well with the iodine value of the oil and also the solid fat index. If a hydrogen gas meter is available, this will have been set at a precalculated amount of gas at which to stop the reaction for determination of the refractive index. Calculation of the amount of gas required is based on the stoichiometry of hydrogenation (Mattil 1964). When the desired refractive index is reached, the batch is cooled for filtration and the solid fat index is determined in the laboratory. This is by far the most important analysis method in hydrogenation control. Typical solid fat indices for selectively and nonselectively hydrogenated canola oil are given in Table IV (Teasdale, 1975). 

Surface refractivity The refractive index, calculated from observations of pressure, temperature, and humidity at the surface of the earth. 

For common optical glasses, the refractive index calculated with the three-term Sellmeier equation deviates from the actual refractive index by less than 5 x 10 over the wavelengths range of365 nm to 2.3 pm, which is of the order of the homogeneity of a glass sample. Additional terms are sometimes added to make the calculation even more precise. In its most general form, the Sellmeier... 

Equation (78) [16, 61] was used with poly(l-olefin) refractive indexes (calculated from i LL molar... 

Mobile phase ethanol/buffer 75/25% v/v pH 4 with 10 mM trietylamine + acetic acid n solute refractive index calculated using the SPARC software (http //ibmlc2.chem.uga.edu/sparc). 

Estimated refractive index, calculated using (2) (with Sm and Sj)... 

In the case of Langmuir monolayers, film thickness and index of refraction have not been given much attention. While several groups have measured A versus a, [143-145], calculations by Knoll and co-workers [146] call into question the ability of ellipsometry to unambiguously determine thickness and refractive index of a Langmuir monolayer. A small error in the chosen index of refraction produces a large error in thickness. A new microscopic imaging technique described in section IV-3E uses ellipsometric contrast but does not require absolute determination of thickness and refractive index. Ellipsometry is routinely used to successfully characterize thin films on solid supports as described in Sections X-7, XI-2, and XV-7. 

We are now in a position to calculate the reflections from multiple mterfaces using the simple example of a thin film of material of thickness d with refractive index n.2 sandwiched between a material of refractive index (where this is generally air witii n = ) deposited onto a substrate of refractive index [35, 36], This is depicted in figure Bl.26.9. The resulting reflectivities for p- and s-polarized light respectively are given by ... 

Determination of the physical constants and the establishment of the purity of the compound. For a solid, the melting point is of great importance if recrystalhsation does not alter it, the compound may be regarded as pure. For a hquid, the boiling point is first determined if most of it distils over a narrow range (say, 1-2°), it is reasonably pure. (Constant boUing point mixtures, compare Section 1,4, are, however known.) The refractive index and the density, from which the molecular refractivity may be calculated, are also valuable constants for liquids. 

Computed optical properties tend not to be extremely accurate for polymers. The optical absorption spectra (UV/VIS) must be computed from semiempiri-cal or ah initio calculations. Vibrational spectra (IR) can be computed with some molecular mechanics or orbital-based methods. The refractive index is most often calculated from a group additivity technique, with a correction for density. 

The refractive index of moist air can be calculated from the expression... 

The refractive index of CCI4 at 20°C and 589 nm, the D line of the sodium spectrum, is 1.4607. At this temperature the density of this compound is 1.59 g cm . Use this information to calculate a for CCI4. Criticize or defend the following proposition The prediction that = f(R/X) may have been premature. The consideration of Eq. (10.3) which led to this conclusion could just as well predict = f(a /X). 

Suspended particles are the most important factor in visibility reduction. In most instances, the visual quality of air is controlled by partide scattering and is characterized by the extinction coeffident The size of particles plays a crucial role in their interaction with light. Other factors are the refractive index and shape of the particles, although their effect is harder to measure and is less well understood. If we could establish these properties, we could calculate the amount of light scattering and absorption. Alternatively, the extinction coeffident associated with an aerosol can be measured directly. 

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