scholarly journals The Role of Electric Fields and Ion Concentrations in the Formation and Stabilization of High-n Rydberg States

1998 ◽  
Vol 18 (1-2) ◽  
pp. 13-33 ◽  
Author(s):  
A. Held ◽  
E. W. Schlag
Keyword(s):  
Electric Fields ◽  
Rydberg States ◽  
Ion Concentration ◽  
Late Time ◽  
Weakly Bound ◽  
Ion Concentrations ◽  
Zero Kinetic Energy ◽  
Ionization Limit ◽  
Static Electric Fields

ZEro Kinetic Energy (ZEKE) spectroscopy relies on electrons produced through delayed field ionization of the narrow band of high-n Rydberg states which exist just below the ionization limit of each ionic eigenstate. Using the unique properties of these weakly bound, stable, high-n Rydberg states (ZEKE states) below the ionization limit rather than the unbound states above the limit, as in PES, leads to an improvement in resolution of more than two orders of magnitude. Several different types of ZEKE experiments, each designed to probe the formation and stability of these states, are presented here. These experiments were performed with pulsed and static electric fields of different magnitude and duration at different ion concentrations. The results indicate an enhanced ZEKE state decay with increasing electric field strengths and an enhanced formation and stabilization with increasing ion concentrations. A strong interplay between field strength and ion concentration ZEKE state formation is demonstrated. The strong influence of electric fields and ion concentrations on the physical properties of the ZEKE state, above and below the classical ionization threshold, is also demonstrated through late time (tens of microseconds) decay rate measurements.

A Unified Mechanism for the Production of ZEKE States

1996 ◽  
Vol 51 (12) ◽  
pp. 1236-1246
Author(s):  
A. Held ◽  
L. Ya. Baranov ◽  
H. L. Selzle ◽  
E. W. Schlag
Keyword(s):  
High Resolution ◽  
Electric Fields ◽  
Molecular System ◽  
Rydberg States ◽  
Molecular Ions ◽  
Experimental Results ◽  
Ion Concentrations ◽  
The Stability ◽  
Static Electric Fields ◽  
The Continuum

Abstract ZEKE states are highly stabilized Rydberg states which exist below each ionic eigenstate of a molecular system even high up into the continuum. The stability and neutrality of these states is the basis on which the high resolution ZEKE technique for the study of molecular ions is built upon. A new mechanism is proposed for the production of ZEKE states from optically accessible, relatively short lived Rydberg states. The mechanism is based on experimental results for a range of fields and ion concentrations. The experiments were performed with pulsed and static electric fields of different magnitudes at various ion concentrations.

scholarly journals Functionalized Silicon Electrodes Toward Electrostatic Catalysis

2021 ◽  
Vol 9 ◽  
Author(s):  
Long Zhang ◽  
Xiaohua Yang ◽  
Shun Li ◽  
JianMing Zhang
Keyword(s):  
Electric Fields ◽  
Silicon Surfaces ◽  
Double Layers ◽  
External Electric Fields ◽  
Space Charges ◽  
Surface Models ◽  
Solid Liquid ◽  
Static Electric Fields ◽  
Mediator Catalysis

Oriented external electric fields are now emerging as “smart effectors” of chemical changes. The key challenges in experimentally studying electrostatic catalysis are (i) controlling the orientation of fields along the reaction axis and (ii) finely adjusting the magnitudes of electrostatic stimuli. Surface models provide a versatile platform for addressing the direction of electric fields with respect to reactants and balancing the trade-off between the solubility of charged species and the intensity of electric fields. In this mini-review, we present the recent advances that have been investigated of the electrostatic effect on the chemical reaction on the monolayer-functionalized silicon surfaces. We mainly focus on elucidating the mediator/catalysis role of static electric fields induced from either solid/liquid electric double layers at electrode/electrolyte interfaces or space charges in the semiconductors, indicating the electrostatic aspects is of great significance in the semiconductor electrochemistry, redox electroactivity, and chemical bonding. Herein, the functionalization of silicon surfaces allows scientists to explore electrostatic catalysis from nanoscale to mesoscale; most importantly, it provides glimpses of the wide-ranging potentials of oriented electric fields for switching on/off the macroscale synthetic organic electrochemistry and living radical polymerization.

scholarly journals The Discrepancy Between Simulation and Observation of Electric Fields in Collisionless Shocks

2021 ◽  
Vol 7 ◽  
Author(s):  
Lynn B. Wilson ◽  
Li-Jen Chen ◽  
Vadim Roytershteyn
Keyword(s):  
Time Series ◽  
Electric Fields ◽  
Recent Time ◽  
Small Scale ◽  
Collisionless Shocks ◽  
High Frequencies ◽  
Electrostatic Fields ◽  
Static Electric Fields

Recent time series observations of electric fields within collisionless shocks have shown that the fluctuating, electrostatic fields can be in excess of one hundred times that of the quasi-static electric fields. That is, the largest amplitude electric fields occur at high frequencies, not low. In contrast, many if not most kinetic simulations show the opposite, where the quasi-static electric fields dominate, unless they are specifically tailored to examine small-scale instabilities. Further, the shock ramp thickness is often observed to fall between the electron and ion scales while many simulations tend to produce ramp thicknesses at least at or above ion scales. This raises numerous questions about the role of small-scale instabilities and about the ability to directly compare simulations with observations.

MQDT operatorial formalism analysis of molecular Rydberg states in weak electric fields : application to Na2

1991 ◽  
Vol 1 (8) ◽  
pp. 875-897 ◽  
Author(s):  
P. F. Brevet ◽  
Ch. Bordas ◽  
M. Broyer ◽  
G. Jalbert ◽  
P. Labastie
Keyword(s):  
Electric Fields ◽  
Rydberg States

Transport and fluctuations in nonlinear-dissipative systems: role of interparticle collisions

1999 ◽  
Vol 4 ◽  
pp. 31-86 ◽  
Author(s):  
R. Katilius ◽  
A. Matulionis ◽  
R. Raguotis ◽  
I. Matulionienė
Keyword(s):  
Electric Fields ◽  
Carrier Density ◽  
Experimental Results ◽  
Dissipative Systems ◽  
Doped Semiconductors ◽  
Electron Diffusion ◽  
Electron Collisions ◽  
Electric Noise ◽  
Diffusion Phenomena

The goal of the paper is to overview contemporary theoretical and experimental research of the microwave electric noise and fluctuations of hot carriers in semiconductors, revealing sensitivity of the noise spectra to non-linearity in the applied electric field strength and, especially, in the carrier density. During the last years, investigation of electronic noise and electron diffusion phenomena in doped semiconductors was in a rapid progress. By combining analytic and Monte Carlo methods as well as the available experimental results on noise, it became possible to obtain the electron diffusion coefficients in the range of electric fields where inter-electron collisions are important and Price’s relation is not necessarily valid. Correspondingly, a special attention to the role of inter-electron collisions and of the non-linearity in the carrier density while shaping electric noise and diffusion phenomena in the non-equilibrium states will be paid. The basic and up-to-date information will be presented on methods and advances in this contemporary field - the field in which methods of non-linear analytic and computational analysis are indispensable while seeking coherent understanding and interpretation of experimental results.

scholarly journals Millimeter (MM) wave and microwave frequency radiation produce deeply penetrating effects: the biology and the physics

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Martin L. Pall
Keyword(s):  
Magnetic Fields ◽  
Electric Fields ◽  
Cardiac Activity ◽  
Maximum Level ◽  
Voltage Sensor ◽  
The Body ◽  
Time Varying ◽  
The Brain ◽  
Mm Waves

Abstract Millimeter wave (MM-wave) electromagnetic fields (EMFs) are predicted to not produce penetrating effects in the body. The electric but not magnetic part of MM-EMFs are almost completely absorbed within the outer 1 mm of the body. Rodents are reported to have penetrating MM-wave impacts on the brain, the myocardium, liver, kidney and bone marrow. MM-waves produce electromagnetic sensitivity-like changes in rodent, frog and skate tissues. In humans, MM-waves have penetrating effects including impacts on the brain, producing EEG changes and other neurological/neuropsychiatric changes, increases in apparent electromagnetic hypersensitivity and produce changes on ulcers and cardiac activity. This review focuses on several issues required to understand penetrating effects of MM-waves and microwaves: 1. Electronically generated EMFs are coherent, producing much higher electrical and magnetic forces then do natural incoherent EMFs. 2. The fixed relationship between electrical and magnetic fields found in EMFs in a vacuum or highly permeable medium such as air, predicted by Maxwell’s equations, breaks down in other materials. Specifically, MM-wave electrical fields are almost completely absorbed in the outer 1 mm of the body due to the high dielectric constant of biological aqueous phases. However, the magnetic fields are very highly penetrating. 3. Time-varying magnetic fields have central roles in producing highly penetrating effects. The primary mechanism of EMF action is voltage-gated calcium channel (VGCC) activation with the EMFs acting via their forces on the voltage sensor, rather than by depolarization of the plasma membrane. Two distinct mechanisms, an indirect and a direct mechanism, are consistent with and predicted by the physics, to explain penetrating MM-wave VGCC activation via the voltage sensor. Time-varying coherent magnetic fields, as predicted by the Maxwell–Faraday version of Faraday’s law of induction, can put forces on ions dissolved in aqueous phases deep within the body, regenerating coherent electric fields which activate the VGCC voltage sensor. In addition, time-varying magnetic fields can directly put forces on the 20 charges in the VGCC voltage sensor. There are three very important findings here which are rarely recognized in the EMF scientific literature: coherence of electronically generated EMFs; the key role of time-varying magnetic fields in generating highly penetrating effects; the key role of both modulating and pure EMF pulses in greatly increasing very short term high level time-variation of magnetic and electric fields. It is probable that genuine safety guidelines must keep nanosecond timescale-variation of coherent electric and magnetic fields below some maximum level in order to produce genuine safety. These findings have important implications with regard to 5G radiation.

scholarly journals Elucidating the Influence of Electric Fields toward CO2 Activation on YSZ (111)

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 271
Author(s):  
Nisa Ulumuddin ◽  
Fanglin Che ◽  
Jung-Il Yang ◽  
Su Ha ◽  
Jean-Sabin McEwen
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Heterogeneous Catalysts ◽  
Co2 Reduction ◽  
Total Density ◽  
Reverse Water Gas Shift ◽  
High Thermodynamic Stability ◽  
Shift Reaction ◽  
Water Gas

Despite its high thermodynamic stability, the presence of a negative electric field is known to facilitate the activation of CO2 through electrostatic effects. To utilize electric fields for a reverse water gas shift reaction, it is critical to elucidate the role of an electric field on a catalyst surface toward activating a CO2 molecule. We conduct a first-principles study to gain an atomic and electronic description of adsorbed CO2 on YSZ (111) surfaces when external electric fields of +1 V/Å, 0 V/Å, and −1 V/Å are applied. We find that the application of an external electric field generally destabilizes oxide bonds, where the direction of the field affects the location of the most favorable oxygen vacancy. The direction of the field also drastically impacts how CO2 adsorbs on the surface. CO2 is bound by physisorption when a +1 V/Å field is applied, a similar interaction as to how it is adsorbed in the absence of a field. This interaction changes to chemisorption when the surface is exposed to a −1 V/Å field value, resulting in the formation of a CO3− complex. The strong interaction is reflected through a direct charge transfer and an orbital splitting within the Olatticep-states. While CO2 remains physisorbed when a +1 V/Å field value is applied, our total density of states analysis indicates that a positive field pulls the charge away from the adsorbate, resulting in a shift of its bonding and antibonding peaks to higher energies, allowing a stronger interaction with YSZ (111). Ultimately, the effect of an electric field toward CO2 adsorption is not negligible, and there is potential in utilizing electric fields to favor the thermodynamics of CO2 reduction on heterogeneous catalysts.

The role of high Rydberg states in enhanced O-formation in a pulsed O2discharge

1999 ◽  
Vol 8 (3) ◽  
pp. 384-391 ◽  
Author(s):  
W X Ding ◽  
L A Pinnaduwage ◽  
C Tav ◽  
D L McCorkle
Keyword(s):  
Rydberg States
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