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CARACTERIZAÇÃO DE NANOPARTICULAS E NANOESTRUTURAS Aula 10 QF933 Instituto de Química UNICAMP. Nanoparticles Characterization: Measurement of the particles size by the PCS technique. MSc. Priscyla D. Marcato Dr. Nelson Durán. Principle of Measurement.
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Measurement of the particles size by the PCS technique
MSc. Priscyla D. Marcato
Dr. Nelson Durán
Particles, emulsions and molecules in suspension undergo Brownian motion.
This is the motion induced by the bombardment by solvent molecules that themselves are moving due to their thermal energy
Temperature and viscosity must be known
Small particles- noisy curve
Large particles- smooth curve
The velocity of the Brownian motion is defined by a property known as the translational diffusion coefficient (usually given the symbol, D).
= 633 nm
Zetasizer Nano ZS
Determined autocorrelation function
Correlogram from a sample containing small particles
turbidity is linear with concentration
Particles are so close together that the scattered radiation is re-scattered by other particles.
(For nanoparticles less than d =λ/10 or around 60nm the scattering will be equal in all
This particles will scatter 106 (one million) times more light than the small particle (8 nm)
The contribution to the total light scattered by the small particles will be extremely small
r = d/2
V= 4(d/2)3 = 4d3
5 nm and 50 nm
(in equal number)
Which of these distributions should I use?
Direct determination of the number-weighted mean radius and polydispersity from dynamic light-scattering data
Philipus et al.,Applied Optics, 45, 2209 (2006)
We find that converting intensity-weighted distributions is not always reliable, especially when the polydispersity of the sample is large.
Dynamic Light Scattering:An Introduction in 30 Minutes, Malvern, http://www.malvern.co.uk/common/downloads/campaign/MRK656-01.pdf
Homogeneização a frio
Homogeneização a quente
Solução de tensoativo (quente)
(sob alta agitação)
Moído (micropartículas lipídicas)
Solução de tensoativo (fria)
Homogeneizado à alta Pressão
19, 11-16 (2002).
Sakulkhul et al., Proceedings
of the 2nd IEEE International