Interaction Between Colloidal Particles in A.C. Electric Fields in the Relaxation Region of Double Layers

1992 ◽  
Vol 289 ◽  
Author(s):  
Yue Hu ◽  
Seth Fraden ◽  
J. L. Glass ◽  
L. E. Wenner
Keyword(s):  
Computer Simulation ◽  
External Field ◽  
Electric Fields ◽  
Colloidal Particles ◽  
Dipole Moments ◽  
Colloidal Suspension ◽  
Double Layers ◽  
Electric Dipole Moments ◽  
Small Inhomogeneity ◽  
Recent Computer

When an electric field is applied to a colloidal suspension of micronsize particles, the particles are attracted to each other in the direction of the external field. They line up to form chains and columns across the gap of the electrodes and therefore drastically change the rheological properties of the suspension. These electrorheological phenomena have been studied extensively by recent computer simulation work [1,2], and it is generally accepted that the interactions between the induced electric dipole moments of the particles are responsible for their alignment in the external fields. To avoid net migrations of particles in electric fields of small inhomogeneity, alternating fields are generally used in experiments.

Particle Compaction with Alternating Electric Fields: The Effects of Electrode Geometry

1986 ◽  
Vol 73 ◽  
Author(s):  
Alan J. Hurd
Keyword(s):  
Electric Fields ◽  
Colloidal Particles ◽  
Dielectric Material ◽  
Double Layers ◽  
Electrode Geometry ◽  
Dipole Interactions ◽  
Alternating Electric Fields ◽  
Alternating Electric Field ◽  
Dc Bias ◽  
Induced Dipoles

ABSTRACTA technique for inducing ordered, close-packed arrangements of various symmetries among colloidal particles is discussed. An external alternating electric field applied to the colloid induces dipole interactions of variable strength by polarizing either the dielectric material of the particles or their electrostatic double layers. Ordering in various symmetries can be obtained by switching the field rapidly between pairs of electrodes, thereby changing the orientation of the induced dipoles. A small dc bias serves to deposit and compact the aligned particles.

Characterization of interactive force acting on colloidal particles near an electrode in presence of a high-frequency (>10 kHz) AC electric field using particle diffusometry

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Kshitiz Gupta ◽  
Dong Hoon Lee ◽  
Steven T. Wereley ◽  
Stuart J. Williams
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Particle Motion ◽  
Electrode Surface ◽  
High Frequency ◽  
Colloidal Particles ◽  
Low Frequency ◽  
Double Layers ◽  
Average Height ◽  
Ac Electric Field

Colloidal particles like polystyrene beads and metallic micro and nanoparticles are known to assemble in crystal-like structures near an electrode surface under both DC and AC electric fields. Various studies have shown that this self-assembly is governed by a balance between an attractive electrohydrodynamic (EHD) force and an induced dipole-dipole repulsion (Trau et al., 1997). The EHD force originates from electrolyte flow caused by interaction between the electric field and the polarized double layers of both the particles and the electrode surface. The particles are found to either aggregate or repel from each other on application of electric field depending on the mobility of the ions in the electrolyte (Woehl et al., 2014). The particle motion in the electrode plane is studied well under various conditions however, not as many references are available in the literature that discuss the effects of the AC electric field on their out-of-plane motion, especially at high frequencies (>10 kHz). Haughey and Earnshaw (1998), and Fagan et al. (2005) have studied the particle motion perpendicular to the electrode plane and their average height from the electrode mostly in presence of DC or low frequency AC (<1 kHz) electric field. However, these studies do not provide enough insight towards the effects of high frequency (>10 kHz) electric field on the particles’ motion perpendicular to the electrode plane.  

scholarly journals Permanent electric dipole moments of single-, two- and three-nucleon systems

2017 ◽  
Vol 26 (01n02) ◽  
pp. 1740031 ◽  
Author(s):  
Andreas Wirzba ◽  
Jan Bsaisou ◽  
Andreas Nogga
Keyword(s):  
Electric Fields ◽  
Electric Dipole ◽  
Dipole Moments ◽  
New Physics ◽  
Finite System ◽  
Light Nuclei ◽  
Window Of Opportunity ◽  
Matrix Elements ◽  
Electric Dipole Moments ◽  
The Standard Model

A nonzero electric dipole moment (EDM) of the neutron, proton, deuteron or helion, in fact, of any finite system necessarily involves the breaking of a symmetry, either by the presence of external fields (i.e., electric fields leading to the case of induced EDMs) or explicitly by the breaking of the discrete parity and time-reflection symmetries in the case of permanent EDMs. We discuss two theorems describing these phenomena and report about the cosmological motivation for an existence of [Formula: see text] breaking beyond what is generated by the Kobayashi–Maskawa mechanism in the Standard Model and what this might imply for the permanent EDMs of the nucleon and light nuclei by estimating a window of opportunity for physics beyond what is currently known. Recent — and in the case of the deuteron even unpublished — results for the relevant matrix elements of nuclear EDM operators are presented and the relevance for disentangling underlying New Physics sources is discussed.

Atom control and gravity measurements using Rydberg positronium

2014 ◽  
Vol 30 ◽  
pp. 1460259 ◽  
Author(s):  
D. B. Cassidy ◽  
S. D. Hogan
Keyword(s):  
Electric Fields ◽  
Direct Measurement ◽  
Electric Dipole ◽  
Dipole Moments ◽  
Rydberg States ◽  
Free Fall ◽  
Gravity Measurement ◽  
Electric Dipole Moments ◽  
Gravity Measurements ◽  
Recent Developments

We consider some of the obstacles that will have to be overcome in order to perform a direct measurement of the gravitational free-fall of positronium atoms. Foremost among these are the production of positronium atoms in a cryogenic environment, efficient excitation of these atoms to suitably long-lived Rydberg states, and their subsequent control via the interaction of their large electric dipole moments with inhomogeneous electric fields. Recent developments in all of these areas can be directly applied to a positronium free-fall gravity measurement, making such an endeavour both timely and feasible.

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