Magneto-spatial dispersional effect in a diamagnetic molecular system in d.c. electric field

The ability to control the chemical conformation of a system via external stimuli is a promsing route for developing molecular switches. For eventual deployment as viable sub-nanoscale components that are compatible with current electronic device technology, conformational switching should controllable by a local electric field (i.e. E-field gateable) and accompanied by a rapid change in conduction. In organic chemical systems the degree of π-conjugation is linked to the degree of electronic delocalisation, and thus largely determines the conductivity. Here, by means of accurate first principles calculations, we study the prototypical biphenyl based molecular system in which the dihedral angle between the two rings determines the degree of conjugation. In order to make this a gateable system we create a net dipole by asymmetrically functionalising one ring with electronegative substituents (F, Br and CN) with different polarisabilities. In this way, the application of an E-field interacts with the dipolar system to influence the dihedral angle, thus controlling the conjugation. For all three considered substituents we consider a range of E-fields, and in each case extract conformational energy profiles. Using this data we obtain the minimum E-field required to induce a barrierless switching event for each system. We further extract the estimated switching speeds, the conformational probabliities at finite temperatures, and the effect of applied E-field on electronic structure. Consideration of these data allow us to assess which factors are most important in the design of efficient gateable electrical molecular switches.

Download Full-text

Electric field effects on fluorescence of pyrene in a homogeneously distributed system and in an oriented molecular system

Journal of Luminescence ◽

10.1016/s0022-2313(99)00379-8 ◽

2000 ◽

Vol 87-89 ◽

pp. 733-735 ◽

Cited By ~ 3

Author(s):

Nobuhiro Ohta ◽

Shiro Umeuchi ◽

Takayuki Kanada ◽

Kazunari Akita ◽

Hiroshi Kawabata ◽

...

Keyword(s):

Electric Field ◽

Distributed System ◽

Molecular System ◽

Electric Field Effects ◽

Field Effects

Download Full-text

Twistable Dipolar Aryl Rings as Electric Field Actuated Conformational Molecular Switches

10.26434/chemrxiv.13031843.v1 ◽

2020 ◽

Author(s):

Kílian Jutglar Lozano ◽

Raul Santiago ◽

Jordi Ribas ◽

Stefan Bromley

Keyword(s):

Electric Field ◽

Dihedral Angle ◽

Electronic Device ◽

Molecular System ◽

Rapid Change ◽

Molecular Switches ◽

Organic Chemical ◽

Chemical Systems ◽

Dipolar System ◽

External Stimuli

The ability to control the chemical conformation of a system via external stimuli is a promsing route for developing molecular switches. For eventual deployment as viable sub-nanoscale components that are compatible with current electronic device technology, conformational switching should controllable by a local electric field (i.e. E-field gateable) and accompanied by a rapid change in conduction. In organic chemical systems the degree of π-conjugation is linked to the degree of electronic delocalisation, and thus largely determines the conductivity. Here, by means of accurate first principles calculations, we study the prototypical biphenyl based molecular system in which the dihedral angle between the two rings determines the degree of conjugation. In order to make this a gateable system we create a net dipole by asymmetrically functionalising one ring with electronegative substituents (F, Br and CN) with different polarisabilities. In this way, the application of an E-field interacts with the dipolar system to influence the dihedral angle, thus controlling the conjugation. For all three considered substituents we consider a range of E-fields, and in each case extract conformational energy profiles. Using this data we obtain the minimum E-field required to induce a barrierless switching event for each system. We further extract the estimated switching speeds, the conformational probabliities at finite temperatures, and the effect of applied E-field on electronic structure. Consideration of these data allow us to assess which factors are most important in the design of efficient gateable electrical molecular switches.

Download Full-text

Modeling of Solute-Solvent Interactions Using an External Electric Field—From Tautomeric Equilibrium in Nonpolar Solvents to the Dissociation of Alkali Metal Halides

Molecules ◽

10.3390/molecules26051283 ◽

2021 ◽

Vol 26 (5) ◽

pp. 1283 ◽

Cited By ~ 1

Author(s):

Ilya G. Shenderovich ◽

Gleb S. Denisov

Keyword(s):

Electric Field ◽

Solvent Effect ◽

External Electric Field ◽

Molecular System ◽

Tautomeric Equilibrium ◽

Continuum Approximation ◽

Solvent Interactions ◽

Reaction Field ◽

Nonpolar Solvents ◽

Quantum Chemistry Calculations

An implicit account of the solvent effect can be carried out using traditional static quantum chemistry calculations by applying an external electric field to the studied molecular system. This approach allows one to distinguish between the effects of the macroscopic reaction field of the solvent and specific solute–solvent interactions. In this study, we report on the dependence of the simulation results on the use of the polarizable continuum approximation and on the importance of the solvent effect in nonpolar solvents. The latter was demonstrated using experimental data on tautomeric equilibria between the pyridone and hydroxypyridine forms of 2,6-di-tert-butyl-4-hydroxy-pyridine in cyclohexane and chloroform.

Download Full-text

Resolution in photoelectron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086593 ◽

1991 ◽

Vol 49 ◽

pp. 458-459

Author(s):

G. F. Rempfer

Keyword(s):

Electron Microscopy ◽

Electric Field ◽

Ultraviolet Light ◽

Uniform Field ◽

Virtual Image ◽

Lens System ◽

Photoemission Electron Microscopy ◽

Planar Electrode ◽

Electron Lens ◽

Photoemission Electron

In photoelectron microscopy (PEM), also called photoemission electron microscopy (PEEM), the image is formed by electrons which have been liberated from the specimen by ultraviolet light. The electrons are accelerated by an electric field before being imaged by an electron lens system. The specimen is supported on a planar electrode (or the electrode itself may be the specimen), and the accelerating field is applied between the specimen, which serves as the cathode, and an anode. The accelerating field is essentially uniform except for microfields near the surface of the specimen and a diverging field near the anode aperture. The uniform field forms a virtual image of the specimen (virtual specimen) at unit lateral magnification, approximately twice as far from the anode as is the specimen. The diverging field at the anode aperture in turn forms a virtual image of the virtual specimen at magnification 2/3, at a distance from the anode of 4/3 the specimen distance. This demagnified virtual image is the object for the objective stage of the lens system.

Download Full-text

Field-assisted ionization theory for microscopists

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171833 ◽

1994 ◽

Vol 52 ◽

pp. 820-821

Author(s):

Patrick P. Camus

Keyword(s):

Electric Field ◽

Electron Tunneling ◽

Ionization Probability ◽

Critical Distance ◽

Tunneling Probability ◽

Field Ionization ◽

Radius Of Curvature ◽

Field Evaporation ◽

A Value ◽

Ion Emission

The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

Download Full-text