scholarly journals Microscopic mechanisms of cooperative communications within single nanocatalysts

2022 ◽  
Vol 119 (3) ◽  
pp. e2115135119
Author(s):  
Bhawakshi Punia ◽  
Srabanti Chaudhury ◽  
Anatoly B. Kolomeisky
Keyword(s):  
Electric Fields ◽  
Cooperative Communications ◽  
Industrial Applications ◽  
Main Role ◽  
Discrete State ◽  
Correlation Lengths ◽  
Cooperative Effects ◽  
Theoretical Predictions ◽  
Fundamental Research ◽  
Positively Charged

Catalysis is a method of accelerating chemical reactions that is critically important for fundamental research as well as for industrial applications. It has been recently discovered that catalytic reactions on metal nanoparticles exhibit cooperative effects. The mechanism of these observations, however, remains not well understood. In this work, we present a theoretical investigation on possible microscopic origin of cooperative communications in nanocatalysts. In our approach, the main role is played by positively charged holes on metal surfaces. A corresponding discrete-state stochastic model for the dynamics of holes is developed and explicitly solved. It is shown that the observed spatial correlation lengths are given by the average distances migrated by the holes before they disappear, while the temporal memory is determined by their lifetimes. Our theoretical approach is able to explain the universality of cooperative communications as well as the effect of external electric fields. Theoretical predictions are in agreement with experimental observations. The proposed theoretical framework quantitatively clarifies some important aspects of the microscopic mechanisms of heterogeneous catalysis.

scholarly journals Measuring and Leveraging Electrostatic Effects in a Charged Phosphine

2020 ◽  
Author(s):  
Andrew J. McNeece ◽  
Margaret L. Kelty ◽  
Alexander S. Filatov ◽  
John Anderson
Keyword(s):  
Electric Fields ◽  
Phase Reaction ◽  
Reaction Conditions ◽  
Phosphine Selenide ◽  
Molecular Systems ◽  
Common Solution ◽  
Electrostatic Component ◽  
Theoretical Predictions ◽  
Charged Group ◽  
Space Effects

<div>Local electric fields have recently been investigated for optimizing reactivity in synthetic systems. However, disentangling the relative contributions of inductive (through-bond) and electrostatic (through-space) effects in molecular systems has been a long-standing challenge. To understand the interplay of these effects and leverage electrostatic influences for enhanced reactivity, we have synthesized a distally charged phosphine, Ph<sub>2</sub>PCH<sub>2</sub>BF<sub>3</sub><sup>−</sup>, and studied the effect of the charged trifluoroborate group on its donor properties and reactivity. This charged phosphine displays solvent-dependent changes in donor strength as measured by the <i>J</i><sub>P-Se</sub> of the corresponding phosphine selenide. The variation with solvent dielectric illustrates a significant electrostatic component to the donor strength. Computations further support the importance of electrostatic contributions and highlight the effect of charge position and orientation. Finally, this charged group also greatly accelerates C–F oxidative addition reactivity in Ni complexes, experimentally</div><div>verifying recent theoretical predictions. These results show that covalently bound charged functionalities can exert a significant electrostatic influence even under common solution phase reaction conditions.</div>

A New Electrically Reversible Depassivation/Passivation Mechanism in Polycrystalline Silicon

1996 ◽  
Vol 424 ◽  
Author(s):  
Vyshnavi Suntharalingam ◽  
Stephen J. Fonash
Keyword(s):  
Electric Fields ◽  
Polycrystalline Silicon ◽  
Solid Phase ◽  
Hydrogen Release ◽  
Temperature Bias ◽  
Polysilicon Films ◽  
The Stability ◽  
Quartz Substrates ◽  
Hydrogenated Amorphous ◽  
Positively Charged

AbstractAn electrically reversible depassivation/passivation phenomenon, recently found for hydrogen passivated polysilicon [1] is further explored in this report. This reversible effect is seen in both ECR and RE hydrogen passivated n-channel thin film transistors (TFTs) but is not seen in the corresponding hydrogen passivated pchannel TFrs, nor is it seen in either n- or p-channel TETs before hydrogenation. This phenomenon has been observed when room temperature bias stressing TFTs fabricated on solid phase or laser crystallized polysilicon films on quartz substrates [1]. A model involving hydrogen release or capture at defects, positively charged hydrogen motion in device electric fields, and subsequent hydrogen capture at other defects has been proposed. This phenomenon has significant implications for polycrystalline silicon TFT’ design and operation. By extension, it also offers significant insight into the stability problems of hydrogenated amorphous silicon.

Broadband terahertz spectroscopy: principles, fundamental research and potential for industrial applications

2013 ◽  
Vol 34 (6) ◽  
pp. S179-S199 ◽  
Author(s):  
W Zouaghi ◽  
M D Thomson ◽  
K Rabia ◽  
R Hahn ◽  
V Blank ◽  
...  
Keyword(s):  
Terahertz Spectroscopy ◽  
Industrial Applications ◽  
Fundamental Research ◽  
Broadband Terahertz

scholarly journals Toughness Enhancement of PHBV/TPU/Cellulose Compounds with Reactive Additives for Compostable Injected Parts in Industrial Applications

2018 ◽  
Vol 19 (7) ◽  
pp. 2102 ◽  
Author(s):  
Estefanía Sánchez-Safont ◽  
Alex Arrillaga ◽  
Jon Anakabe ◽  
Luis Cabedo ◽  
Jose Gamez-Perez
Keyword(s):  
Thermoplastic Polyurethane ◽  
Industrial Applications ◽  
Main Role ◽  
Cellulose Fibres ◽  
Potential Applications ◽  
Reactive Additives ◽  
Single Use ◽  
Reactive Agents ◽  
Toughness Enhancement

Poly(3-hydroxybutyrate-co-3-valerate), PHBV, is a bacterial thermoplastic biopolyester that possesses interesting thermal and mechanical properties. As it is fully biodegradable, it could be an alternative to the use of commodities in single-use applications or in those intended for composting at their end of life. Two big drawbacks of PHBV are its low impact toughness and its high cost, which limit its potential applications. In this work, we proposed the use of a PHBV-based compound with purified α-cellulose fibres and a thermoplastic polyurethane (TPU), with the purpose of improving the performance of PHBV in terms of balanced heat resistance, stiffness, and toughness. Three reactive agents with different functionalities have been tested in these compounds: hexametylene diisocianate (HMDI), a commercial multi-epoxy-functionalized styrene-co-glycidyl methacrylate oligomer (Joncryl® ADR-4368), and triglycidyl isocyanurate (TGIC). The results indicate that the reactive agents play a main role of compatibilizers among the phases of the PHBV/TPU/cellulose compounds. HMDI showed the highest ability to compatibilize the cellulose and the PHBV in the compounds, with the topmost values of deformation at break, static toughness, and impact strength. Joncryl® and TGIC, on the other hand, seemed to enhance the compatibility between the fibres and the polymer matrix as well as the TPU within the PHBV.

scholarly journals The scattering of hydrogen positive rays, and the existence of a powerful field of force in the hydrogen molecule

1922 ◽  
Vol 102 (715) ◽  
pp. 197-209 ◽  
Keyword(s):  
Electric Fields ◽  
General Scheme ◽  
Hydrogen Gas ◽  
Theoretical Interpretation ◽  
Scattering Medium ◽  
Hydrogen Atoms ◽  
Hydrogen Molecules ◽  
Nuclear Particle ◽  
Positively Charged ◽  
Made In

In view of the extremely important results obtained by Sir E. Rutherford and others from a study of the scattering of α -rays, it seemed worth while to investigate the scattering of particles moving with smaller velocities such as occur in the positive rays. The most interesting, because the simplest, are the rays of positively charged hydrogen atoms, which presumably consist simply of a nuclear particle, or proton. The experiments described in this paper were made in some cases with these rays, in others with the positively charged hydrogen molecules, systems consisting of two protons and one electron. The scattering medium was in all cases hydrogen gas. This was chosen largely for convenience, as the experimental arrangement is considerably simplified if the same gas is used to produce the rays and to scatter them, and also because, with the exception of helium, the molecule of hydrogen is the simplest known, and there seemed more hope of obtaining results which could be given a definite theoretical interpretation. The general scheme of experiment was to produce the rays in a discharge tube, analyse them by magnetic and electric fields in the ordinary way, cut off all except those of the kind required by a slotted diaphragm, pass the remainder through a chamber containing the scattering gas, and receive them in a Faraday cylinder arranged behind a slit of variable width. The experiment consisted in finding how the charge received by the Faraday cylinder varied with the width of the slit, when this was made wider than the geometrical “shadow” of the slot in the diaphragm. Any rays lying outside this “shadow” must have been scattered.

Interplay between Fracture and Domain Switching of Ferroelectrics

2006 ◽  
Vol 306-308 ◽  
pp. 501-510
Author(s):  
Y.Q. Cui ◽  
Wei Yang
Keyword(s):  
Experimental Data ◽  
Crack Initiation ◽  
Electric Fields ◽  
Large Scale ◽  
Inner Core ◽  
Domain Switching ◽  
Global Scale ◽  
Theoretical Predictions ◽  
T Stress ◽  
Cylindrical Inclusions

Applications of above-coercive electric fields lead to domain switching of a large or global scale. Large scale switching model is proposed to deal with load-induced domains witching in experiment. Both a discussion of crack initiation via the stress intensity factor and a discussion of crack path stability via T-stress are presented. The theoretical predictions and the experimental data roughly coincide for crack initiation, propagation and stability phenomena. Attention is also extended to consider the effect of non-uniform ferro-elastic domain switching in the vicinity of a crack. The domain switching zone is divided into a saturated inner core and an active surrounding annulus. Toughening for ferroelectrics with different poling states is estimated via Reuss type approximation. Solutions obtained according to spherical and cylindrical inclusions cover the range of experimental data.

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