Data di Pubblicazione:
2020
Citazione:
Near FIeld Scattering under Forced Flow / L. Cremonesi, M. Siano, B. Paroli, M. Potenza. - In: REVIEW OF SCIENTIFIC INSTRUMENTS. - ISSN 0034-6748. - 91(2020). [10.1063/1.5138694]
Abstract:
We describe a light scattering technique for characterizing colloidal samples under constant flow. It exploits the properties of speckles in the
deep Fresnel region—the so-called near field speckles—providing absolute scattering measurements of the static form factor of the sample, as
described extensively by Mazzoni et al. [Rev. Sci. Instrum. 84, 043704 (2013)] for static samples. We exploit a strongly astigmatic beam for
illuminating the scattering volume with a light sheet a few microns thick. This largely improves the sensitivity of the method to small signals.
Moreover, by flowing the sample in the direction perpendicular to the light sheet, the transit times are reduced to a minimum, allowing
for fast measurements. We tested the instrument with suspensions of calibrated colloidal polystyrene spheres with a size comparable to the
light wavelength. In particular, we recovered the static form factors of suspensions of spherical particles and the phase lag of the zero-angle
scattering amplitude, which both compare well to Mie theory predictions. We then applied the method to colloidal fractal aggregates of
sub-wavelength particles and measured their fractal dimension. The instrument is designed to be operational in continuous flow analysis
systems.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
L. Cremonesi, M. Siano, B. Paroli, M. Potenza
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