Electronic Stopping of Channeled Ions in Silicon

1992 ◽  
Vol 279 ◽  
Author(s):  
Gerhard Hobler ◽  
Hans W. Pötzl
Keyword(s):  
Electron Density ◽  
Stopping Power ◽  
Ion Energy ◽  
Slowing Down ◽  
Dependent Part ◽  
Power Models ◽  
Local Impact ◽  
Parameter Dependent ◽  
Nonlocal Part ◽  
Structure Calculations

ABSTRACTConcentration profiles of channeling and random implants of boron, phosphorus, and arsenic in silicon are compiled from the literature and are analyzed using Monte Carlo simulations. An empirical 3-parameter model of the electronic stopping power is found which yields excellent results for all channeling directions in the energy range of about 20 keV to 1 MeV. The model contains a local impact parameter dependent part and a nonlocal part, the latter increasing with ion energy. In addition, local electron density dependent stopping power models are investigated, using a realistic electron density distribution obtained by first principles band structure calculations. These models fail to describe the slowing down of ions channeled along the <110> axis.

scholarly journals Unveiling the Unexpected Reactivity of Electrophilic Diazoalkanes in [3+2] Cycloaddition Reactions within Molecular Electron Density Theory

2020 ◽  
Author(s):  
Luis R. Domingo ◽  
Mar Ríos-Gutiérrez ◽  
Nivedita Acharjee
Keyword(s):  
Electron Density ◽  
Complete Agreement ◽  
Slowing Down ◽  
Molecular Electron ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Electrophilic Character ◽  
Step Mechanism ◽  
Computational Level ◽  
Density Transfer

The [3+2] cycloaddition (32CA) reactions of strongly nucleophilic norbornadiene (NBD) with simplest diazoalkane (DAA) and three DAAs of increased electrophilicity have been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G(d,p) computational level. These pmr-type 32CA reactions follow an asynchronous one-step mechanism with activation enthalpies ranging from 17.7 to 27.9 kcal&middot;mol-1 in acetonitrile. The high exergonic character of these reactions makes them irreversible. The presence of electron-withdrawing (EW) substituents in the DAA increases the activation enthalpies, in complete agreement with the experimental slowing-down of the reactions, but contrary to the Conceptual DFT prediction. Despite the nucleophilic and electrophilic character of the reagents, the global electron density transfer at the TSs indicates rather non-polar 32CA reactions. The present MEDT study allows establishing that the depopulation of the NNC core in this series of DAAs with the increase of the EW character of the substituents present at the carbon center is responsible for the experimentally found deceleration.

Active vibration control of a blade element with uncertainty modeling in PZT actuator force

2019 ◽  
Vol 25 (21-22) ◽  
pp. 2721-2732
Author(s):  
Selim Sivrioglu ◽  
Fevzi Cakmak Bolat ◽  
Ercan Erturk
Keyword(s):  
Steady State ◽  
Active Vibration Control ◽  
State Space Model ◽  
Uncertainty Modeling ◽  
Aerodynamic Load ◽  
Mixed Norm ◽  
Multi Objective ◽  
Dependent Part ◽  
Parameter Dependent ◽  
Blade Element

The aim of this research is to attenuate the vibrations of a blade structure with an attached piezoelectric actuator using robust multi-objective control. The force obtained from a piezoelectric patch loading has uncertainties due to the complicated shape (airfoil) of the blade element. A parameter-dependent model of the force equation is developed to understand the possible variation range of the actuation force. The modal analysis of the blade is performed to find vibration mode frequencies, and an aerodynamic load is generated experimentally to create steady-state vibration on the blade. A state-space model is obtained by considering certain vibration modes and the parameter-dependent part of the force in the input vector is taken outside of the plant model. The robust stability filter is modified with parameter dependency to have a cluster of the filter. Two different multi-objective controllers are designed with different design objectives. The designed controllers are implemented in experiments and performances of the controllers are compared using frequency and time domain responses. It is shown that the flexible blade vibrations are successfully suppressed with the proposed mixed norm robust controllers under the effect of steady-state aerodynamic disturbance with different air speeds. It is observed in experimental results that the performances of the [Formula: see text] controller are better than the [Formula: see text] controller.

Volume ignition for inertial confinement fusion tested by different stopping power models

1996 ◽  
Author(s):  
H. Hora ◽  
S. Eliezer ◽  
J. J. Honrubia ◽  
R. Höpfl ◽  
J. M. Martinez-Val ◽  
...  
Keyword(s):  
Inertial Confinement Fusion ◽  
Stopping Power ◽  
Inertial Confinement ◽  
Confinement Fusion ◽  
Power Models ◽  
Volume Ignition

scholarly journals Stopping power of a helium plasma under LTE or NLTE conditions

2018 ◽  
Vol 36 (4) ◽  
pp. 442-447
Author(s):  
Luis González-Gallego ◽  
Manuel D. Barriga-Carrasco ◽  
Juan Miguel Gil ◽  
Rafael Rodríguez ◽  
Guadalupe Espinosa
Keyword(s):  
Theoretical Model ◽  
Electron Temperature ◽  
Thermal Equilibrium ◽  
Stopping Power ◽  
Local Thermal Equilibrium ◽  
Helium Plasma ◽  
Slowing Down ◽  
Non Local ◽  
Argon Ions ◽  
Bound Electrons

AbstractIn this work, the stopping power of a partially ionized helium plasma due to its free and bound electrons is analyzed for an electron temperature and density in which local thermal equilibrium (LTE) or non-local thermal equilibrium (NLTE) regimes can be possible. In particular by means of collisional-radiative models, the average ionization of the plasma as well as the abundances of different helium species (HeI, HeII, and HeIII) are analyzed in both LTE and NLTE thermodynamic states. The influence of this ionization and of the different ion abundances on the stopping power of the helium plasma is shown to be quite significant. Finally, our theoretical model is compared with experimental results on slowing down of swift argon ions in helium plasma.

Slowing down of heavy ions in solids near the stopping power maximum

1991 ◽  
Vol 56-57 ◽  
pp. 355-357 ◽  
Author(s):  
A. Abdesselam ◽  
J.P. Stoquert ◽  
G. Guillaume ◽  
M. Hage-Ali ◽  
J.J. Grob ◽  
...  
Keyword(s):  
Heavy Ions ◽  
Stopping Power ◽  
Slowing Down

RANGE AND STOPPING POWER ENERGY RELATIONSHIPS FOR 0.5–30 keV ELECTRON BEAMS SLOWING DOWN IN SOLIDS: ANALYTICAL MODEL

2013 ◽  
Vol 28 (01) ◽  
pp. 1450006 ◽  
Author(s):  
A. BENTABET
Keyword(s):  
Analytical Model ◽  
Electron Beams ◽  
Geometric Model ◽  
Mathematical Expression ◽  
Low Energy ◽  
Stopping Power ◽  
Slowing Down ◽  
Energy Relationships ◽  
Slight Discrepancy ◽  
Good Agreement

The development of an analytical model for calculating the electron stopping power (SP) converging with the experimental data at lower energies is still not completed. The purpose of this work is to suggest a mathematical expression of the range and the stopping power of electrons impinging in solid targets in the energy range up to 30 keV based on the spherical geometric model [A. Bentabet, Vacuum86 (2012) 1855]. The results are in good agreement with those of the literature. The slight discrepancy between the obtained and both the theoretical and experimental results regarding the stopping power at very low energy (E<0.5 keV) is discussed.

scholarly journals Demystifying fluorine chemical shifts: electronic structure calculations address origins of seemingly anomalous 19F-NMR spectra of fluorohistidine isomers and analogues

2015 ◽  
Vol 17 (45) ◽  
pp. 30606-30612 ◽  
Author(s):  
Chandana Kasireddy ◽  
James G. Bann ◽  
Katie R. Mitchell-Koch
Keyword(s):  
Electronic Structure ◽  
Chemical Shift ◽  
Electron Density ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Electronic Structure Calculations ◽  
19F Nmr ◽  
19F Nmr Spectra ◽  
Structure Calculations

Understanding localization/delocalization of fluorine electron density is shown to be critical for predicting and interpreting fluorine chemical shift.

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