Particle sizing in non-dilute dispersions using diffusing wave spectroscopy with multiple optical path lengths

Deconvoluting Emulsion Stabilization Mechanisms Using Diffusing Wave Spectroscopy

“…For a single DWS experiment, a sample cuvette with the dimensions outlined above is filled (∼3.5 mL) completely and the intensity autocorrelation function, g 2 , as well as the average intensity are determined over a 30 s period at detector angles of 30, 60, and 90°. The average intensity is used to determine l * for the sample at the time of measurement by a calibration process outlined by McMillin et al Additionally, the average intensity is used to compute the theoretical variance on the intensity autocorrelation function, first shown for dynamic light scattering measurements by Schätzel and further adapted for DWS by Orsi et al and McMillin et al ,, The error is propagated through the Siegert relationship, and g 2 is converted to g 1 . Using the l * determined via intensity, eq is numerically inverted, and the mean squared displacement is extracted, with propagated error.…”

“…The DWS workflow was developed in a prior work and we refer to it for a more in-depth discussion of the method; however, it will be briefly described here. 15 For a single DWS experiment, a sample cuvette with the dimensions outlined above is filled (∼3. 15,27,28 The error is propagated through the Siegert relationship, and g 2 is converted to g 1 .…”

“…15 For a single DWS experiment, a sample cuvette with the dimensions outlined above is filled (∼3. 15,27,28 The error is propagated through the Siegert relationship, and g 2 is converted to g 1 .…”

“…In this regime, the mean squared displacement scales sublinearly in time. Many models for nondiffusion motion are generally system-specific and lack generality; therefore, in order to parametrize the mean squared displacements extracted from eq we use an anomalous diffusion model, shown below in eq , ⟨ normalΔ r 2 ( τ ) ⟩ = 6 K α t α Equation is fit to all extracted mean squared displacement curves by varying the parameters K α and α. For α = 1, K α is the Brownian diffusion coefficient, for α < 1 the average droplet motion is subdiffusive, and for α > 1 the motion is superdiffusive with a velocity variance.…”

“…To mitigate these drawbacks, we present a method for emulsion stability analysis using DWS. The method presented here builds upon earlier work using DWS to accurately size concentrated suspensions and provides information about emulsion droplet concentration, size, and dynamics . Additionally, using viscosity measurements, the DWS data can help elucidate the mechanism of action for surface-stabilizing molecules in W/O emulsions.…”