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It is often useful to give the gyrofrequency a sign with the definition = or express it in units of hertz with =. For electrons, this frequency can be reduced to , = (/).. In cgs-units the gyroradius = | | and the corresponding gyrofrequency = | | include a factor , that is the velocity of light, because the magnetic field is expressed in units [] = / /.
Since the chain conformations of a polymer sample are quasi infinite in number and constantly change over time, the "radius of gyration" discussed in polymer physics must usually be understood as a mean over all polymer molecules of the sample and over time. That is, the radius of gyration which is measured as an average over time or ensemble:
For this case the radius of gyration is approximated using Flory's mean field approach which yields a scaling for the radius of gyration of: R g ∼ N ν {\displaystyle R_{g}\sim N^{\nu }} , where R g {\displaystyle R_{g}} is the radius of gyration of the polymer, N {\displaystyle N} is the number of bond segments (equal to the degree of ...
A quantity frequently used in polymer physics is the radius of gyration: = It is worth noting that the above average end-to-end distance, which in the case of this simple model is also the typical amplitude of the system's fluctuations, becomes negligible compared to the total unfolded length of the polymer N l {\displaystyle N\,l} at the ...
The main purpose of such scattering experiments involving polymers is to study unique properties of the sample of interest: Determine the polymers "size" - radius of gyration. Evaluating the structural and thermo-statistical behavior of a polymer, i.e. freely-jointed chain / freely-rotating chain etc.
It is defined [8] as = where s b is the mean square radius of gyration of the branched macromolecule in a given solvent, and s l is the mean square radius of gyration of an otherwise identical linear macromolecule in the same solvent at the same temperature. A value greater than 1 indicates an increased radius of gyration due to branching.
As described above, the radius of gyration, R g, and the second virial coefficient, A 2, are also calculated from this equation. The refractive index increment dn/dc characterizes the change of the refractive index n with the concentration c and can be measured with a differential refractometer.
In its coil state, the radius of gyration of the macromolecule scales as its chain length to the three-fifths power. As it passes through the coil–globule transition, it shifts to scaling as chain length to the half power (at the transition) and finally to the one third power in the collapsed state. [4]