scholarly journals Ordering and Dynamics of Interacting Colloidal Particles under Soft Confinement

Author(s):  
Salvador Herrera-Velarde ◽  
Edith Euán-Díaz ◽  
Ramón Castañeda-Priego

Confinement can induce substantial changes in the physical properties of macromolecules in suspension. Soft confinement is a particular class of restriction where the boundaries that constraint the particles in a region of the space are not well-defined. This scenario leads to a broader structural and dynamical behavior than the observed in systems enclosed between rigid walls. In this contribution, we study the ordering and diffusive properties of a two-dimensional colloidal model system subjected to a one-dimensional parabolic trap. Increasing the trap strength makes it possible to go through weak to strong confinement, allowing a dimensional transition from two- to one-dimension. The non-monotonic response of the static and dynamical properties to the gradual dimensionality change affects the system phase behavior. We find that the particle dynamics is connected with the structural transitions induced by the parabolic trap. In particular, at low and intermediate confinement regimes, complex structural and dynamical scenarios arise, where the softness of the external potential induces melting and freezing, resulting in faster and slower particle diffusion, respectively. Besides, at strong confinements, colloids move basically along one direction, and the whole system behaves structurally and dynamically similar to a one-dimensional colloidal system.

2021 ◽  
Vol 5 (2) ◽  
pp. 29
Author(s):  
Salvador Herrera-Velarde ◽  
Edith C. Euán-Díaz ◽  
Ramón Castañeda-Priego

Confinement can induce substantial changes in the physical properties of macromolecules in suspension. Soft confinement is a particular class of restriction where the boundaries that constraint the particles in a region of the space are not well-defined. This scenario leads to a broader structural and dynamical behavior than observed in systems enclosed between rigid walls. In this contribution, we study the ordering and diffusive properties of a two-dimensional colloidal model system subjected to a one-dimensional parabolic trap. Increasing the trap strength makes it possible to go through weak to strong confinement, allowing a dimensional transition from two- to one-dimension. The non-monotonic response of the static and dynamical properties to the gradual dimensionality change affects the system phase behavior. We find that the particle dynamics are connected to the structural transitions induced by the parabolic trap. In particular, at low and intermediate confinement regimes, complex structural and dynamical scenarios arise, where the softness of the external potential induces melting and freezing, resulting in faster and slower particle diffusion, respectively. Besides, at strong confinements, colloids move basically along one direction, and the whole system behaves structurally and dynamically similar to a one-dimensional colloidal system.


1996 ◽  
Vol 10 (20) ◽  
pp. 945-953 ◽  
Author(s):  
B.C.S. GRANDI ◽  
W. FIGUEIREDO

We have studied the behavior of the one-dimensional ferromagnetic Ising model in contact with a heat bath and subject to an external source of energy. The contact with the heat bath is simulated by a process of Glauber type, while the continuous flux of energy into the system by a process of Kawasaki type. We show, within the dynamical pair approximation that the phase diagram exhibits a line of continuous nonequilibrium transitions between the paramagnetic and antiferromagnetic phases. However, detailed Monte Carlo simulations on the same model show clearly that the only stationary state is the paramagnetic one, whatever is the value of the competition parameter between the Glauber and Kawasaki dynamics.


2008 ◽  
Vol 45 (03) ◽  
pp. 879-887 ◽  
Author(s):  
Nader Ebrahimi

Nanosystems are devices that are in the size range of a billionth of a meter (1 x 10-9) and therefore are built necessarily from individual atoms. The one-dimensional nanosystems or linear nanosystems cover all the nanosized systems which possess one dimension that exceeds the other two dimensions, i.e. extension over one dimension is predominant over the other two dimensions. Here only two of the dimensions have to be on the nanoscale (less than 100 nanometers). In this paper we consider the structural relationship between a linear nanosystem and its atoms acting as components of the nanosystem. Using such information, we then assess the nanosystem's limiting reliability which is, of course, probabilistic in nature. We consider the linear nanosystem at a fixed moment of time, say the present moment, and we assume that the present state of the linear nanosystem depends only on the present states of its atoms.


2008 ◽  
pp. 21-28
Author(s):  
Tatjana Kuljanin ◽  
Ljubinko Levic ◽  
Nevena Misljenovic ◽  
Gordana Koprivica

Electrokinetic potential is an important property of colloidal particles and, regarding the fact that it is a well defined and easily measurable property, it is considered to be a permanent characteristic of a particular colloidal system. In fact, it is a measure of electrokinetic charge that surrounds the colloidal particle in a solution and is in direct proportion with the mobility of particles in an electric field. Gouy-Chapman-Stern-Graham's model of electric double layer was adopted and it was proven experimentally that the addition of Cu++ ions to sugar beet pectin caused a reduction in the negative electrokinetic potential proportional to the increase of Cu++ concentration. Higher Cu++ concentrations increased the proportion of cation specific adsorption (Cu++ and H+) with regard to electrostatic Coulombic forces. Consequently, there is a shift in the shear plane between the fixed and diffuse layers directed towards the diffuse layer, i.e. towards its compression and decrease in the electrokinetic potential or even charge inversion of pectin macromolecules.


2017 ◽  
Vol 114 (49) ◽  
pp. 12906-12909 ◽  
Author(s):  
Ricard Alert ◽  
Pietro Tierno ◽  
Jaume Casademunt

Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid–solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field H. At the transition field Hs, the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length ξ∝|H2−Hs2|−1/2. Mean-field critical exponents are predicted, since the upper critical dimension of the transition is du=2. Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.


2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Yalin Zhang ◽  
Yanling Wang ◽  
Guoliang Shi ◽  
Shizhong Liao

We consider all of the transmission eigenvalues for one-dimensional media. We give some conditions under which complex eigenvalues exist. In the case when the index of refraction is constant, it is shown that all the transmission eigenvalues are real if and only if the index of refraction is an odd number or reciprocal of an odd number.


2001 ◽  
Vol 15 (13) ◽  
pp. 1923-1937 ◽  
Author(s):  
P. CHOUDHURY ◽  
A. N. DAS

The ground-state properties of polarons in a one-dimensional chain is studied analytically within the modified Lang–Firsov (MLF) transformation using various phonon-averaging techniques. The object of the work is to examine how the analytical approaches may be improved to give rise to the real picture of polaronic properties as predicted by extensive numerical studies. The results are compared with those obtained from numerical analyses using the density matrix renormalization group (DMRG) and other variational techniques. It is observed that our results agree well with the numerical results particularly in the low and intermediate range of phonon coupling.


2014 ◽  
Vol 25 (08) ◽  
pp. 1450028 ◽  
Author(s):  
L. A. Pastur ◽  
V. V. Slavin ◽  
A. A. Krivchikov

The ground state (GS) of interacting particles on a disordered one-dimensional (1D) host-lattice is studied by a new numerical method. It is shown that if the concentration of particles is small, then even a weak disorder of the host-lattice breaks the long-range order of Generalized Wigner Crystal (GWC), replacing it by the sequence of blocks (domains) of particles with random lengths. The mean domains length as a function of the host-lattice disorder parameter is also found. It is shown that the domain structure can be detected by a weak random field, whose form is similar to that of the ground state but has fluctuating domain walls positions. This is because the generalized magnetization corresponding to the field has a sufficiently sharp peak as a function of the amplitude of fluctuations for small amplitudes.


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