scholarly journals Interplay between Long-Range Crystal Order and Short-Range Molecular Interactions Tunes Carrier Mobility in Liquid Crystal Dyes

2017 ◽  
Vol 9 (7) ◽  
pp. 6228-6236 ◽  
Author(s):  
Nadine Tchamba Yimga ◽  
Charusheela Ramanan ◽  
Holger Borchert ◽  
Jürgen Parisi ◽  
Harald Untenecker ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Long Range ◽  
Molecular Interactions ◽  
Short Range ◽  
Carrier Mobility

scholarly journals Liquid crystal phase of counter-rotating staircases – A case of antiferrochirality

2021 ◽  
Author(s):  
Ya-xin Li ◽  
Hong-fei Gao ◽  
Rui-bin Zhang ◽  
Kutlwano Gabana ◽  
Qing Chang ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Long Range ◽  
Short Range ◽  
Liquid Crystal Phase ◽  
Helical Structures ◽  
New Approach ◽  
Chiroptical Properties ◽  
Pi Conjugated ◽  
Left Handed ◽  
Straight Rod

Abstract Helical structures continue to inspire, and there is considerable temptation to attribute helicity to columnar liquid crystals (LC). While short isohelical sequences are undoubtedly present, and longer ones in chiral or chiral-doped compounds, the order is only short-range, equivalent to a paramagnet without or with field. However, here we report a confirmed example of a true LC phase of achiral compounds consisting of columns, each being a long-range homochiral helix. Long-range periodicity and isochirality are maintained by intercolumnar interaction. This orthorhombic LC, spacegroup Fddd, is discovered in compounds with either bent or straight rod-like pi-conjugated cores. There are 4 right and 4 left-handed ribbons or star-profiled columns per unit cell. The structure is equivalent to an antiferromagnet with twist replacing spins. A theory based on interacting quadrupoles confirms this structure as energetically favoured over alternatives. The findings open a new approach to homochirality in achiral compounds, with promising optical/chiroptical properties.

Intermolecular forces

1975 ◽  
Vol 272 (915) ◽  
pp. 5-12 ◽  
Keyword(s):  
Long Range ◽  
Molecular Interactions ◽  
Short Range ◽  
Intermolecular Forces ◽  
Electron Exchange ◽  
Inverse Power ◽  
Charge Distributions ◽  
Electrostatic Component ◽  
Electrostatic Induction ◽  
Long Range Interactions

The nature of molecular interactions is examined. Intermolecular forces are divided into long-range and short-range components; the former operate at distances where the effects of electron exchange are negligible and decrease as an inverse power of the separation. The long-range interactions may be subdivided into electrostatic, induction and dispersion contributions, where the electrostatic component is the interaction of the permanent charge distributions and the others originate in the fluctuations in the distributions. Typical magnitudes of the various contributions are given. The forces between macroscopic bodies are briefly considered, as are the effects of a medium. Some of the manifestations of molecular interactions are discussed.

Spontaneous Lateral Composition Modulation in III-V Semiconductor Alloys

MRS Bulletin ◽  
1997 ◽  
Vol 22 (7) ◽  
pp. 38-43 ◽  
Author(s):  
J. Mirecki Millunchick ◽  
R.D. Twesten ◽  
S.R. Lee ◽  
D.M. Follstaedt ◽  
E.D. Jones ◽  
...  
Keyword(s):  
Long Range ◽  
High Speed ◽  
Short Range ◽  
Carrier Mobility ◽  
Alloy System ◽  
Semiconductor Alloys ◽  
Chemical Ordering ◽  
Short Range Ordering ◽  
Device Structures ◽  
Long Range Ordering

The application of III-V semiconductor alloys in device structures is of importance for high-speed microelectronics and optoelectronics. These alloys have allowed the device engineer to tailor material parameters such as the bandgap and carrier mobility to the need of the device by altering the alloy composition. When using ternary or quaternary materials, the device designer presumes that the alloy is completely disordered, without any correlation between the atoms on the cation (anion) sublattice. However the thermodynamics of the alloy system often produce material that has some degree of macroscopic or microscopic ordering. Short-range ordering occurs when atoms adopt correlated neighboring positions over distances of the order of a few lattice spacings. This can be manifested as the preferential association of like atoms, as in clustering, or of unlike atoms, as in chemical ordering (e.g., CuPt ordering). Long-range ordering occurs over many tens of lattice spacings, as in the case of phase separation. In either short-range or long-range ordering, the band structure and the crystal symmetry are greatly altered. Therefore it is absolutely critical that the mechanisms be fully understood to prevent ordering when necessary or to exploit it when possible.

scholarly journals Structural basis of long-range to short-range synaptic transition in NHEJ

Nature ◽  
2021 ◽  
Author(s):  
Siyu Chen ◽  
Linda Lee ◽  
Tasmin Naila ◽  
Susan Fishbain ◽  
Annie Wang ◽  
...  
Keyword(s):  
Long Range ◽  
Short Range ◽  
Structural Basis

scholarly journals Comparison of short-range order in irradiated dysprosium titanates

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Roman Sherrod ◽  
Eric C. O’Quinn ◽  
Igor M. Gussev ◽  
Cale Overstreet ◽  
Joerg Neuefeind ◽  
...  
Keyword(s):  
Long Range ◽  
Short Range ◽  
Structural Model ◽  
Ion Irradiation ◽  
Function Analysis ◽  
Ion Beam ◽  
Structural Response ◽  
Heavy Ion ◽  
Range Order ◽  
Radiation Resistant

AbstractThe structural response of Dy2TiO5 oxide under swift heavy ion irradiation (2.2 GeV Au ions) was studied over a range of structural length scales utilizing neutron total scattering experiments. Refinement of diffraction data confirms that the long-range orthorhombic structure is susceptible to ion beam-induced amorphization with limited crystalline fraction remaining after irradiation to 8 × 1012 ions/cm2. In contrast, the local atomic arrangement, examined through pair distribution function analysis, shows only subtle changes after irradiation and is still described best by the original orthorhombic structural model. A comparison to Dy2Ti2O7 pyrochlore oxide under the same irradiation conditions reveals a different behavior: while the dysprosium titanate pyrochlore is more radiation resistant over the long-range with smaller degree of amorphization as compared to Dy2TiO5, the former involves more local atomic rearrangements, best described by a pyrochlore-to-weberite-type transformation. These results highlight the importance of short-range and medium-range order analysis for a comprehensive description of radiation behavior.

SHORT-RANGE AND LONG-RANGE ORDER OF TITANIUM IN Ti1+xS2

1977 ◽  
Vol 38 (C7) ◽  
pp. C7-202-C7-206 ◽  
Author(s):  
R. MORET ◽  
M. HUBER ◽  
R. COMÈS
Keyword(s):  
Long Range ◽  
Short Range ◽  
Range Order ◽  
Long Range Order

scholarly journals Short range smectic order driving long range nematic order: example of cuprates

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
R. S. Markiewicz ◽  
J. Lorenzana ◽  
G. Seibold ◽  
A. Bansil
Keyword(s):  
Long Range ◽  
Short Range ◽  
Nematic Order

ANDERSON LOCALIZATION FOR A MULTIDIMENSIONAL MODEL INCLUDING LONG RANGE POTENTIALS AND DISPLACEMENTS

2002 ◽  
Vol 14 (03) ◽  
pp. 273-302 ◽  
Author(s):  
HERIBERT ZENK
Keyword(s):  
Long Range ◽  
Anderson Model ◽  
Anderson Localization ◽  
Short Range ◽  
Energy Interval ◽  
Multidimensional Model ◽  
Short Summary

We give a short summary on how to combine and extend results of Combes and Hislop [2] (short range Anderson model with additional displacements), Kirsch, Stollmann and Stolz [13] and [14] (long range Anderson model without displacements) to get localization in an energy interval above the infimum of the almost sure spectrum for a continuous multidimensional Anderson model including long range potentials and displacements.

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