Table of Contents
What is refractive index increment?
The refractive index increment (dn/dc) of a solution is a constant that indicates the variation of the refractive index with the solute concentration. It is used in the multi-angle light scattering technique to determine the concentration and the weight-average molar mass of polymers.
What is DN dc value?
What is dn/dc? The key parameter for translating RI detector output to exact sample concentration is the dn/dc value, or refractive index increment. This value is unique for a sample-solvent combination, as it represents the difference in refractive index between the sample and the solvent.
How is DN DC calculated?
By measuring the refractive index of the solvent and for a series of different sample concentrations, the refractive index increment dn/dc can be derived by plotting the refractive index difference between sample solution and pure solvent versus sample concentration. The slope of the plot yields dn/dc.
What is DN DC in SEC MALS?
The quantity dn/dc, also called the “specific refractive index increment” describes how much the refractive index of a polymer solution changes with respect to the concentration of the solute.
What does the refractive index represent?
Refractive Index (Index of Refraction) is a value calculated from the ratio of the speed of light in a vacuum to that in a second medium of greater density. The refractive index variable is most commonly symbolized by the letter n or n’ in descriptive text and mathematical equations.
How is the index of refraction of a medium determined?
The refractive index of a medium (n) is equal to the speed of light (c) divided by the velocity of light through the medium (v). Rearranging the equation allows us to see the relationship regarding v. The lower the refractive index, the faster the velocity of light.
What is a Zimm plot?
An easy graphical way to perform data fitting corresponding to the description given in the section on the Rayleigh Ratio is the so-called Zimm plot. For small and we can equivalently write. From this equations we see that, with data for , we could plot as a function of the mass concentration.
How do you read the refractive index scale?
To read the index of refraction, depress the switch on the left hand side of the refractometer until you see the scale through the eyepiece. This is a view of what the scale will look like. The upper scale indicates the index of refraction. By carefully interpolating you should get 4 decimal place accuracy.
Why is index of refraction greater than or equal to 1?
The value of the index of refraction mostly comes out to be equal to or greater than 1, as the speed of light in a vacuum is always higher than the speed of light in any other medium.
What is RI analysis?
Refractive index (RI) detection is commonly used for the analysis of compounds that do not have good absorption bands for UV light. For such compounds, other detection techniques can be used as well, such as MS or evaporative light scattering detection (ELSD).
What is the formula of refractive index of prism?
The refractive index of prism μ=sin2Asin[2(A+D)]
What is the unit of refractometer?
Brix Scale and Common Brix % The Brix scale is calibrated to the number of grams of cane sugar contained in 100 mL of water. Therefore, the Brix % reading equals actual sugar Concentration.
What is nD in refractive index?
The most common characteristic quantity for characterization of an optical glass is the refractive index n in the middle range of the visible spectrum. This principal refractive index is usually denoted as nd – the refractive index at the wavelength 587.56 nm or in many cases as ne at the wavelength 546.07 nm.