Calculation of Cross Sections for Zero Activation Energy Processes by Simple Collision Models with Emphasis on the Penning Effect

1962 ◽  
Vol 128 (1) ◽  
pp. 210-212 ◽  
Author(s):  
Eldon E. Ferguson
Keyword(s):  
Activation Energy ◽  
Cross Sections ◽  
Energy Processes ◽  
Penning Effect ◽  
Collision Models

scholarly journals Nonlinear corrections on the parametrization methods

2021 ◽  
Vol 81 (9) ◽  
Author(s):  
G. R. Boroun ◽  
B. Rezaei
Keyword(s):  
Cross Sections ◽  
Direct Method ◽  
Nonlinear Behavior ◽  
High Energy ◽  
Structure Functions ◽  
Distribution Functions ◽  
Reduced Cross Section ◽  
Color Dipole ◽  
Wide Range ◽  
Energy Processes

AbstractWe present nonlinear corrections (NLCs) to the distribution functions at low values of x and $$Q^{2}$$ Q 2 using the parametrization $$F_{2}(x,Q^{2})$$ F 2 ( x , Q 2 ) and $$F_{L}(x,Q^{2})$$ F L ( x , Q 2 ) . We use a direct method to extract nonlinear corrections to the ratio of structure functions and the reduced cross section in the next-to-next-to-leading order (NNLO) approximation with respect to the parametrization method (PM). Comparisons between the nonlinear results with the bounds in the color dipole model (CDM) and HERA data indicate the consistency of the nonlinear behavior of the gluon distribution function at low x and low $$Q^{2}$$ Q 2 . The nonlinear longitudinal structure functions are comparable with the H1 Collaboration data in a wide range of $$Q^{2}$$ Q 2 values. Consequently, the nonlinear corrections at NNLO approximation to the reduced cross sections at low and moderate $$Q^{2}$$ Q 2 values show good agreement with the HERA combined data. These results at low x and low $$Q^{2}$$ Q 2 can be applied to the LHeC region for analyses of ultra-high-energy processes.

New low activation energy processes in La2CuO4+δ by elastic energy loss experiments

1997 ◽  
Vol 282-287 ◽  
pp. 1429-1430 ◽  
Author(s):  
G. Cannelli ◽  
R. Cantelli ◽  
F. Cordero ◽  
F. Trequattrini ◽  
M. Ferretti
Keyword(s):  
Activation Energy ◽  
Energy Loss ◽  
Elastic Energy ◽  
Energy Processes

Advanced of Rare Earth Fluorides Technology

2015 ◽  
Vol 1085 ◽  
pp. 229-232
Author(s):  
Tatyana D. Malinovskaya ◽  
Roman A. Nefedov ◽  
Ouna B. Sambueva ◽  
Victor Sachkov
Keyword(s):  
Activation Energy ◽  
Rare Earth ◽  
Apparent Activation Energy ◽  
Rare Earth Metals ◽  
Complex Compounds ◽  
Thermochemical Processes ◽  
Energy Processes ◽  
Rare Earth Fluorides

The thermochemical processes of synthesis and purification of rare earth metals fluorides through the transfer of fluoroammonium complexes were discussed. By differential thermal calorimetry the temperature maxima of rates of formation and decomposition of complex compounds were defined and the values of the apparent activation energy processes were determined. It is possible the use of fluoroammonium systems to develop the preparation of anhydrous fluorides of rare earth metals.

scholarly journals Influence of Divacancy-Oxygen Defects on Recombination Properties of n-Si Subjected to Irradiation and Subsequent Annealing

2018 ◽  
Vol 63 (12) ◽  
pp. 1095
Author(s):  
M. M. Kras’ko ◽  
A. G. Kolosiuk ◽  
V. V. Voitovych ◽  
V. Yu. Povarchuk ◽  
I. S. Roguts’kyi
Keyword(s):  
Activation Energy ◽  
Temperature Interval ◽  
Cross Sections ◽  
Nonequilibrium Charge Carrier ◽  
Frequency Factor ◽  
Czochralski Method ◽  
Free Electron Concentration ◽  
Oxygen Defects ◽  
Doubly Charged ◽  
Charge Carrier Lifetime

The variation of recombination properties in n-Si grown by the Czochralski method, doped to the free electron concentration n0 ∼ 10^14 ÷10^16 cm^−3, irradiated with 60Co y-quanta or 1-MeV electrons, and isochronously annealed for 20 min in the temperature interval 180–380∘C, in which divacancy-oxygen (V2O) complexes are formed and annealed, has been studied in detail. The nonequilibrium charge carrier lifetime т is found to significantly decrease after the annealing in a temperature interval from 180 to 280∘C, with the effect being stronger for low-resistive n-Si. It is shown that a change in т after the annealing at 180–380∘C is caused by divacancy defects, most probably V2O. By analyzing the experimental data with the help of the Shockley–Read–Hall statistics, it is found that the formation of V2O defects is characterized by an activation energy of 1.25±0.05 eV and a frequency factor of (1±0.5)×10^9 s^−1, and their annealing by an activation energy of 1.54±0.09 eV and a frequency factor of (2.1±1.4)×10^10 s^−1. The values of the hole capture cross-sections by singly and doubly charged acceptor states of V2O are obtained as: (5±2)×10^−13 and (8±4)×10^−12 cm^2, respectively.

Laboratory studies of electron attachment and detachment processes of aeronomic interest

1969 ◽  
Vol 47 (10) ◽  
pp. 1783-1793 ◽  
Author(s):  
A. V. Phelps
Keyword(s):  
Cross Sections ◽  
Ion Beam ◽  
Electron Attachment ◽  
Negative Ions ◽  
High Energy ◽  
Low Energy ◽  
Rate Coefficients ◽  
Dissociative Attachment ◽  
Three Body ◽  
Energy Processes

Techniques for the study of electron attachment and detachment are reviewed. The rate coefficients for the various processes of aeronomic interest are then discussed. The rates of three-body and dissociative attachment by thermal electrons have been successfully determined by swarm techniques and by high frequency studies of electrons produced by high energy particles and by photoionization. Collisional and associative detachment rates for thermal energy negative ions have been measured using the swarm and flowing afterglow techniques. Radiative attachment rates for some atmospheric negative ions have been calculated from measurements of photodetachment cross sections using crossed photon and ion beam techniques. Electron beam studies and measurements of ion kinetic energy have provided much useful information regarding the dissociative attachment process and the structure of molecular negative ions. Rate coefficients for low energy processes such as the three-body attachment to O2, the radiative attachment to O, and the associative detachment of O− in collisions with various atmospheric gases are reasonably well known. Other possibly important low energy processes, such as dissociative attachment to O3, radiative attachment to O2, and the associative detachment of O2− are less well known.

scholarly journals Proton Transfer and Kinetic Isotope Effect in Morita-Baylis-Hillman Reaction Under Solvent Effects. a Detailed Computational Study

2021 ◽  
Author(s):  
Veejendra Yadav
Keyword(s):  
Activation Energy ◽  
Proton Transfer ◽  
Isotope Effect ◽  
Solvent Effects ◽  
Kinetic Isotope Effect ◽  
Computational Study ◽  
Kinetic Isotope ◽  
Experimental Findings ◽  
Energy Processes ◽  
Rate Limiting

Solvent effects of CH<sub>2</sub>Cl<sub>2</sub>, CH<sub>3</sub>CN, THF and DMSO on the profile of the Morita-Baylis-Hillman (MBH) reaction were discovered to lower the activation energy of aldol step. Proton-transfer through seven-membered TS state structure enroute Hofmann elimination and also the four-membered TS structure are sufficiently low energy processes in comparison to aldol reaction and, hence, unlikely to contribute to the overall kinetics of the reaction. As an exception, proton-transfer through seven-membered TS structure constitutes the rate-controlling event for the DABCO-catalyzed reaction of methyl acrylate with <i>p</i>-nitrobenzaldehyde under the solvent effects of DMSO. The acetal route was not found to contribute to kinetic isotope effect, which has otherwise been measured to be as high as 5.2 ± 0.6. The simultaneous proton-transfer to the aldol-derived alkoxide and abstraction of proton from the a-carbon of activated alkene by hydroxylic solvents was found to be barrier-less. The reported catalysis by hydroxylic solvents is therefore likely by lowering the activation energy of the aldol step due to activation of aldehyde possibly by protonation or hydrogen-bonding. The present computational results are in excellent agreement with the more than three decade old experimental findings of Hill and Isaacs.<sup> </sup>These authors have reported the aldol step as rate-limiting and absolutely no kinetic isotope effect.

scholarly journals Proton Transfer and Kinetic Isotope Effect in Morita-Baylis-Hillman Reaction Under Solvent Effects. a Detailed Computational Study

2021 ◽  
Author(s):  
Veejendra Yadav
Keyword(s):  
Activation Energy ◽  
Proton Transfer ◽  
Isotope Effect ◽  
Solvent Effects ◽  
Kinetic Isotope Effect ◽  
Computational Study ◽  
Kinetic Isotope ◽  
Experimental Findings ◽  
Energy Processes ◽  
Rate Limiting

Solvent effects of CH<sub>2</sub>Cl<sub>2</sub>, CH<sub>3</sub>CN, THF and DMSO on the profile of the Morita-Baylis-Hillman (MBH) reaction were discovered to lower the activation energy of aldol step. Proton-transfer through seven-membered TS state structure enroute Hofmann elimination and also the four-membered TS structure are sufficiently low energy processes in comparison to aldol reaction and, hence, unlikely to contribute to the overall kinetics of the reaction. As an exception, proton-transfer through seven-membered TS structure constitutes the rate-controlling event for the DABCO-catalyzed reaction of methyl acrylate with <i>p</i>-nitrobenzaldehyde under the solvent effects of DMSO. The acetal route was not found to contribute to kinetic isotope effect, which has otherwise been measured to be as high as 5.2 ± 0.6. The simultaneous proton-transfer to the aldol-derived alkoxide and abstraction of proton from the a-carbon of activated alkene by hydroxylic solvents was found to be barrier-less. The reported catalysis by hydroxylic solvents is therefore likely by lowering the activation energy of the aldol step due to activation of aldehyde possibly by protonation or hydrogen-bonding. The present computational results are in excellent agreement with the more than three decade old experimental findings of Hill and Isaacs.<sup> </sup>These authors have reported the aldol step as rate-limiting and absolutely no kinetic isotope effect.

Solution of the Boltzmann equation for a reacting gas mixture

1993 ◽  
Vol 342 (1665) ◽  
pp. 413-438 ◽  
Keyword(s):  
Activation Energy ◽  
Boltzmann Equation ◽  
Cross Sections ◽  
Bimolecular Reaction ◽  
Model Parameters ◽  
Gas Mixture ◽  
Hard Sphere Model ◽  
Heat Of Reaction ◽  
Exothermic Reactions ◽  
The Boltzmann Equation

A spatially homogeneous gas mixture consisting of structureless molecules of kind A, B, C, D is considered in which the reversible bimolecular reaction A+B ^ C+D occurs. The Boltzmann equation describing this model gas is solved numerically by using the multigroup method. The collision cross sections correspond to the reactive hard sphere model. Parameters are the heat of reaction, the activation energy and the steric factor. Emphasis in the presentation of the results is laid on highly exothermic reactions with large activation energy, in which case the gas undergoes a thermal explosion. It is found that the corrections of the chemical rate constants due to translational non-equilibrium effects are noticeable. The result is a shortening of the reaction period by up to 25%.

scholarly journals HIGH ENERGY PHOTON-PHOTON AND ELECTRON-PHOTON COLLISIONS

1998 ◽  
Vol 13 (14) ◽  
pp. 2417-2427 ◽  
Author(s):  
STANLEY J. BRODSKY
Keyword(s):  
Cross Sections ◽  
High Energy ◽  
Quadrupole Moments ◽  
Gauge Bosons ◽  
Energy Photon ◽  
Virtual Photons ◽  
The Standard Model ◽  
And Other Gauge Bosons ◽  
Electron Photon ◽  
Energy Processes

The advent of a next linear e±e- collider and back-scatterd laser beams will allow the study of a vast array of high energy processes of the Standard Model through the fusion of real and virtual photons and other gauge bosons. As examples, I discuss virtual photon scattering γ*γ*→X in the region dominated by BFKL hard Pomeron exchange and report the predicted cross sections at present and future e±e- colliders. I also discuss exclusive γγ reactions in QCD as a measure of hadron distribution amplitudes and a new method for measuring the anomalous magnetic and quadrupole moments of the W and Z gauge bosons to high precision in polarized electron-photon collisions.

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