Volume 115, Number 4, August 2016
|Number of page(s)||5|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||27 September 2016|
Investigating the time dynamics of photon sequences scattered by tracer particles immersed in a polymeric gel
1 Departamento de Ciencias Básicas, Universidad Autónoma Metropolitana-Azcapotzalco Av. San Pablo 180, 02200 Ciudad de México, Mexico
2 ARPAB - 85100 Potenza, Italy
3 Departamento de Física, CINVESTAV-IPN - Av. Instituto Politécnico Nacional 2508, 07360 Ciudad de México, Mexico
4 Programa de Doctorado en Nanociencias y Nanotecnología, CINVESTAV-IPN Av. Instituto Politécnico Nacional 2508, 07360 Ciudad de México, Mexico
5 CNR, Institute of Methodologies for Environmental Analysis - C.da S. Loja, 85050 Tito (PZ), Italy
Received: 24 June 2016
Accepted: 8 September 2016
By dynamic light scattering, we study the effects of spatial confinement of tracer colloidal particles immersed in polyacrylamide networks on the time dynamics of sequences of elapsed times of scattered photons. We vary the degree of particles spatial confinement by changing the concentration of crosslinker in solution, from 0 to 2% in monomer mass fraction, which allows us to change the elasticity of the polymer gel. By calculating the Allan factor of the point processes of scattered photons arrival times, we are able to characterize the statistical properties of the scattering process. For all the samples we find that: i) the statistics of the photon arrival times is not Poissonian but clusterized in a certain counting time interval; ii) the time dynamics of the photon sequences is fractal in an ample range of counting times, from ∼10−3 to ∼10−1 s, with scaling exponents ranging between ∼1.7 and ∼1.0; iii) the crosslinking density of the polymer network, and thus, the system elasticity is correlated with the value of the fractal exponent. The value of the fractal exponent decreases as the system elasticity, or tracer's spatial confinement, increases.
PACS: 71.20.Rv – Polymers and organic compounds / 78.35.+c – Brillouin and Rayleigh scattering; other light scattering / 05.45.Df – Fractals
© EPLA, 2016
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