Characterization of polymers by dynamic light scattering

Effect of solvent quality and sidechain architecture on conjugated polymer chain conformation in solution

“…37 This makes both DLS and SLS harder as the solution strongly absorbs the red light and the thermal lens effect distorts the optical light path. 38 This leads to a significant broadening of the beam path and a distorted transmission beam, as shown in Fig. S10.…”

Differential Dynamic Microscopy: Diffusion Measurements Where You Want Them

“…The confocal design of the aforementioned KMX-6 instrument enables very low q measurements, but dust suppression could be a challenge and the acquisition times will be DDM-like: long. Measurement of large particles by DLS also requires the user to avoid unwanted detection of scattering stimulated by the back-reflected main beam, either by tilting the cell or by an inside-the-cell beamstop . Finally, DLS of very large scatterers without detection of multiply scattered light may require special steps to avoid number fluctuations.…”

“…The physics community usually favors correlation times, while the DLS community generally favors decay rates. In DLS, plotting the apparent diffusion coefficient, D app , or the hydrodynamic radius, R h , from the Stokes−Einstein relation, against q 2 is a good way to test for sample uniformity in terms of shape and/or size 45 or to test for end-over-end tumbling of large objects. These plots will likely be flat in most DDM experiments in free solution because light is gathered from comparatively low angles and the distances probed are long.…”

“…Colored samples present no problem to DDM or MPT, as they sometimes do to DLS, where the tightly focused laser beam may cause thermal lensing with attendant beam expansion and reduced optical coherence. 45 In strongly absorptive samples, a DLS laser beam may not even reach the center of the cell with usable intensity, nor the scattered light leave it. Using the microscope as a platform for imaging in DDM provides multiple options with respect to image collection and contrast enhancement.…”

“…Measurement of large particles by DLS also requires the user to avoid unwanted detection of scattering stimulated by the back-reflected main beam, either by tilting the cell or by an inside-the-cell beamstop. 45 Finally, DLS of very large scatterers without detection of multiply scattered light may require special steps to avoid number fluctuations. These unwanted changes in intensity due to the number of particles in the viewing volume add to the desired fluctuations arising from motions over the distance 2π/q.…”