Refractive index determination

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4 - angle of the light beam after hitting the sample 

A few drops of the liquid sample are placed on the bottom prism. The refractive index can be read directly from the built-in scale, looking into the refrac-tometer. 

Reffactometry is the last analysis method discussed in this part of the book. However, some more analysis methods can be found in chapter 8 of this book. The reason to describe these analysis methods in another chapter is the high importance attached to these methods for asphaltene chemistry, which is an important part of crude oil chemistry. 

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To correct a refractive index determined for airjliquid to the absolute index vacutimlliquid, the observed value should be multiplied by I 00029. This correction is, however, too small to be of the slightest value in practice. 

Why are sugar and alcohol content in foods commonly determined by refractive index determinations ... 

The amount of polymer adsorbed on each sample was measured by pressure filtration through a 0.1 m filter, followed by analysis of the filtrate for residual polymer by gel permeation chromatography with refractive index determination. Particle zeta potentials were measured by taking a small sample of the solids from the centrifuge and re-suspending them in the supernatant prior to analysis in a Malvern Instruments Zetasizer . The concentration of all other types of ions in the supernatant was analysed by ICP atomic emission spectroscopy. 

Reference electrode, 1104, 1108, 1113 potential, 819, 874 Refractive index, determination with ellipsometry, 1148. 1151 Reflection coefficient, 1151 Residence time, definition, 1310 Reversal techniques, determination of intermediate radicals, 1416 Reversible adsorption of organic molecules, 969, 970... 

Refractive Index. Determine RI at 20°C using an accurate refractometer such as Abbe (See SGA Scientific Inc, Bloomfield, NJ Catalog (1972), p 742 or other suppliers... 

No carbon was recorded for the D-treated film. The O/Si composition ratio was found to be 2.08 and is attributed to the extent of condensation as the organic phase has been removed completely. Based on the amount of Si for sample D and assuming a density of 2.3 g cm3 for amorphous SiC>2, the top layer would correspond to a thickness of 154 nm, if a dense layer is assumed. As the actual layer thickness is 458 nm, this would imply a porosity of 66%. Here a considerable discrepancy with the porosity obtained from ellipsometry is evident. In this respect it should be noted that the RBS measurement was done more to the edge of the sample than ellisometry, where the thickness is smaller than in the centre. Further, the refractive index determined with ellipsometry is very accurate. However, the relation of porosity with refractive index depends on the model used. 

Iodobenzene [591-50-4], C6HBI, mol wt 204.02, 62.23% I, mp —30°C, bp 188—189°C, is a colodess liquid that rapidly becomes yellow and has a characteristic odor. It is insoluble in water, but completely miscible with alcohol, chloroform, and ether. It has a density of 1.832 g/mL at 20°C and a refractive index of 1.621 at 4°C. Iodobenzene is prepared by the reaction of iodine and benzene in the presence of an oxidizing agent and from benzeneiazonium sulfate and potassium iodide (122). Iodobenzene is used as a heavy liquid for refractive index determinations, but probably its principal use is in the synthesis of iodoso compounds, RIO iodoxy compounds, RI02 and iodonium salts, R IX. 

Many of the thinner platelets are transparent and a rich ruby-red color in transmission. They give a uniaxial negative interference figure. The crystals are too deeply colored for refractive index determination, but the mean value is greater than 2. 

Finally, n was determined by spectroscopic ellipsometry. The main drawback with this technique when applied to anisotropic samples is that the measured ellipsometric functions tanlF and cos A are related both to the incidence angle and the anisotropic reflectance coefficient for polarizations parallel and perpendicular to the incidence plane. The parameters thus have to be deconvolved from a set of measurements performed with different orientations of the sample [see (2.15) and (2.16)]. The complex refractive index determined by ellipsometry is reliable only in the spectral region where the sample can be considered as a bulk material. In fact, below the absorption... 

Refractive Index Determine as directed under Refractive Index, Appendix IIB, using an Abbe or other refractometer of equal or greater accuracy. 

Angular Rotation Determine as directed under Optical (Specific) Rotation, Appendix IIB, using a 100-mm tube. Ester Value Determine as directed under Ester Value, Appendix VI, using about 5 g of sample, accurately weighed. Refractive Index Determine as directed under Refractive Index, Appendix IIB, using an Abbe or other refractometer of equal or greater accuracy. 

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