Such an aggregate rotates at a constant angular velocity, leading to periodic changes in the intensity of the scattered light. 1) and the scattering of light will vary depending on the orientation. However, this measurement scheme requires a significantly smaller (several μL) volume of the test suspension as compared to a cuvette in the standard equipment.Īfter the aggregation of SiO 2 spheres the formed particles are not ideally spherical (see the right panel in Fig. Initially, the results do not significantly differ from those obtained in a traditional cuvette, 12 as should be expected. Using the necessary physical parameters, we obtained the SiO 2 spheres diameter of 465 nm. 1 shows single exponential decay with the relaxation time τ = 1.20 ms. Reduction of the size of the droplet due to water evaporation leads to the formation of SiO 2 aggregates in the droplet volume, as evidenced by the increase in relaxation time from 10 -3 to 10 -1 s, as well as by an increase of ACF amplitude. Curve 1 and inset 1’ correspond to the start time ( t = 0) 2 and 2′ – t =10 min 3 – t = 40 min 4 – t = 60 min 5 – t = 90 min 6 and 6′ – t = 120 min. The temporal evolution of the ACF for a single millimetre-sized water droplet that contained SiO 2 spheres of 450 nm diameter and evaporated over 120 min, reducing size from 2.05 mm to 1.15 mm. Interest in droplet-based microfluidic systems has been growing in past decades. Micro-droplets of diverse suspensions/nano-fluids are applied in various sectors of science and industry. We have studied the possibility of using the DLS method to study the internal composition/structure evolution of macro- and micro-droplets of various liquids containing spherical SiO 2 particles. Nevertheless, there are many commercial devices that can be connected to any computer for measuring nanoparticle sizes with the method of dynamic light scattering at high measurement speed. Thus, the DLS has serious limitations in experimental practice. However, two similar particle sizes in a poly-disperse system can be resolved only if they differ by a factor of at least 2-3. The average particle size of each component and the relative contribution of each component to the scattering intensity must be considered. For poly-disperse samples, the interpretation of the experimental data becomes more complicated. However, only for the case of light scattering by mono-disperse spherical particles the processing of the experimental data is simple. To prevent multiple light scattering the concentration of particles should be small.
1- 3 Traditionally, DLS measurements use fluids in rectangular cells and register scattered light at an optimum angle of 90 degrees. in the volume containing particles in a dispersion medium. Dynamic light scattering (DLS) is an investigation method suitable for determination of particle size, size distribution, relaxation processes, etc.
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