scholarly journals Anisotropic electrostatic screening of charged colloids in nematic solvents

2021 ◽  
Vol 7 (5) ◽  
pp. eabd0662
Author(s):  
Jeffrey C. Everts ◽  
Bohdan Senyuk ◽  
Haridas Mundoor ◽  
Miha Ravnik ◽  
Ivan I. Smalyukh
Keyword(s):  
Self Assembly ◽  
Colloidal Particles ◽  
Dielectric Anisotropy ◽  
Debye Screening Length ◽  
Surface Charges ◽  
Screening Length ◽  
Charged Colloids ◽  
Effective Pair ◽  
Anisotropic Elastic ◽  
Pair Interactions

The physical behavior of anisotropic charged colloids is determined by their material dielectric anisotropy, affecting colloidal self-assembly, biological function, and even out-of-equilibrium behavior. However, little is known about anisotropic electrostatic screening, which underlies all electrostatic effective interactions in such soft or biological materials. In this work, we demonstrate anisotropic electrostatic screening for charged colloidal particles in a nematic electrolyte. We show that material anisotropy behaves markedly different from particle anisotropy. The electrostatic potential and pair interactions decay with an anisotropic Debye screening length, contrasting the constant screening length for isotropic electrolytes. Charged dumpling-shaped near-spherical colloidal particles in a nematic medium are used as an experimental model system to explore the effects of anisotropic screening, demonstrating competing anisotropic elastic and electrostatic effective pair interactions for colloidal surface charges tunable from neutral to high, yielding particle-separated metastable states. Generally, our work contributes to the understanding of electrostatic screening in nematic anisotropic media.

Mesoscopically Periodic Photonic-Crystal Materials for Linear and Nonlinear Optics and Chemical Sensing

MRS Bulletin ◽  
1998 ◽  
Vol 23 (10) ◽  
pp. 44-50 ◽  
Author(s):  
Sanford A. Asher ◽  
John Holtz ◽  
Jesse Weissman ◽  
Guisheng Pan
Keyword(s):  
Photonic Crystal ◽  
Self Assembly ◽  
Colloidal Particles ◽  
Spherical Particles ◽  
Infrared Light ◽  
Face Centered Cubic ◽  
X Rays ◽  
Bragg Condition ◽  
Surface Charges ◽  
Diffract Light

Over the past decade, we have been working to develop intelligent photonic-crystal materials with unique properties, which will be useful in a number of technological areas. These photonic-crystal materials utilize mesoscopically periodic arrays of spherical particles as their active optical elements and are easily fabricated chemically by the use of crystalline-colloidal-array (CCA) self-assembly techniques.Crystalline colloidal arrays are mesoscopically periodic fluid materials, which efficiently diffract light meeting the Bragg condition. These photonic-crystal materials consist of arrays of colloidal particles that self-assemble in solution into either face-centered-cubic (fcc) or body-centered-cubic (bcc) crystalline arrays (Figure 1), with lattice constants in the mesoscale size range (50-500 nm). Just as atomic crystals diffract x-rays that meet the Bragg condition, CCAs diffract ultraviolet, visible, and near-infrared light, depending on the lattice spacing; the diffraction phenomena resemble those of opals, which are close-packed arrays of monodisperse silica spheres.The CCA however can be prepared as macroscopically ordered arrays of non-close-packed spheres. This self-assembly is the result of electrostatic repulsions between colloidal particles, each of which has numerous charged surface functional groups. We have concentrated on the development of CCAs that diffract light in the visible spectral region and generally utilize colloidal particles of ~100-nm diameter. These particles have thousands of surface charges, which result from the ionization of surface sulfonate groups. The nearest-neighbor distances are often >200 nm.

scholarly journals Self-Assembly of Shape-Tunable Oblate Colloidal Particles into Orientationally Ordered Crystals, Glassy Crystals and Plastic Crystals

Soft Matter ◽  
2021 ◽  
Author(s):  
Jiawei Lu ◽  
Xiangyu Bu ◽  
Xinghua Zhang ◽  
Bing Liu
Keyword(s):  
Crystal Structures ◽  
Self Assembly ◽  
Colloidal Particles ◽  
Building Blocks ◽  
Fundamental Question ◽  
The Self ◽  
Plastic Crystals ◽  
Self Assembled ◽  
Glassy Crystals ◽  
The Relationship

The shapes of colloidal particles are crucial to the self-assembled superstructures. Understanding the relationship between the shapes of building blocks and the resulting crystal structures is an important fundamental question....

scholarly journals On the Appearance of a Cooper Minimum in the Photoionization Cross Sections of the Plasma-Embedded Li Atom

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Satyabrata Sahoo ◽  
Y. K. Ho
Keyword(s):  
Cross Sections ◽  
Ground State ◽  
Debye Screening Length ◽  
Debye Screening ◽  
Screening Length ◽  
Screening Effect ◽  
Plasma Environment ◽  
Plasma Screening ◽  
Debye Plasma

The plasma screening effect is found to uncover a Cooper minimum in the photoionization cross sections from the ground state of the Li atom embedded in Debye plasma environment. The variation of the location of this minimum with Debye screening length is discussed and analyzed in terms of the instability of the ground state.

Determination of effective pair interactions and segregation behavior at alloy surfaces

Vacuum ◽  
1990 ◽  
Vol 41 (1-3) ◽  
pp. 446-448 ◽  
Author(s):  
H Dreyssé ◽  
G Ceder ◽  
D de Fontaine ◽  
L.T. Wille
Keyword(s):  
Segregation Behavior ◽  
Effective Pair ◽  
Pair Interactions

scholarly journals Transformation between elastic dipoles, quadrupoles, octupoles, and hexadecapoles driven by surfactant self-assembly in nematic emulsion

2021 ◽  
Vol 7 (25) ◽  
pp. eabg0377
Author(s):  
Bohdan Senyuk ◽  
Ali Mozaffari ◽  
Kevin Crust ◽  
Rui Zhang ◽  
Juan J. de Pablo ◽  
...  
Keyword(s):  
Self Assembly ◽  
Molecular Alignment ◽  
Smart Windows ◽  
Equilibrium Dynamics ◽  
Fundamental Science ◽  
Pair Interactions ◽  
Isotropic Fluid

Emulsions comprising isotropic fluid drops within a nematic host are of interest for applications ranging from biodetection to smart windows, which rely on changes of molecular alignment structures around the drops in response to chemical, thermal, electric, and other stimuli. We show that absorption or desorption of trace amounts of common surfactants can drive continuous transformations of elastic multipoles induced by the droplets within the uniformly aligned nematic host. Out-of-equilibrium dynamics of director structures emerge from a controlled self-assembly or desorption of different surfactants at the drop-nematic interfaces, with ensuing forward and reverse transformations between elastic dipoles, quadrupoles, octupoles, and hexadecapoles. We characterize intertransformations of droplet-induced surface and bulk defects, probe elastic pair interactions, and discuss emergent prospects for fundamental science and applications of the reconfigurable nematic emulsions.

Sign in / Sign up

Export Citation Format

Share Document