• Categoría: Artículo
  • Título: Investigating the time dynamics of photon sequences scattered by tracer particles immersed in a polymeric gel
  • Autor (es): Catalina Haro-Pérez, Michele Lovallo, L. Rebeca Moreno-Torres, Alejandro Ramirez-Rojas, Luis F. Rojas-Ochoa, Angel B. Zuccolotto-Bernez and Luciano Telesca
  • Revista: Europhysics Letter
  • Volumen: 115
  • Páginas: 47004
  • Formato: Enlace
  • Subido por: Catalina Ester

Investigating the time dynamics of photon sequences scattered by tracer particles immersed in a polymeric gel

Catalina Haro-Pérez, Michele Lovallo, L. Rebeca Moreno-Torres, Alejandro Ramirez-Rojas, Luis F. Rojas-Ochoa, Angel B. Zuccolotto-Bernez and Luciano Telesca

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.