scholarly journals FORMATION OF LIGHT IMPURITIES IN A HYDROGEN PLASMA AT INITIAL STAGE OF A DISCHARGE

2019 ◽  
pp. 110-112
Author(s):  
V.B. Yuferov ◽  
E.I. Skibenko ◽  
V.I. Tkachov ◽  
V.V. Katrechko ◽  
A.S. Svichkar
Keyword(s):  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Hydrogen Plasma ◽  
Hydrogen Ions ◽  
Hydrogen Atoms ◽  
Impurity Atoms ◽  
Radiation Fluxes ◽  
Start Up ◽  
Initial Stage ◽  
Light Impurities

Analyzing the dynamics of density for atomic and molecular hydrogen ions, the values of atomic hydrogen and UV radiation fluxes to the walls of the plasma chamber were obtained, resulting in light impurities of carbon and oxygen at plasma start-up during the process of desorption from the walls under irradiation. The fluxes of impurity atoms associated with the fluxes of photons and hydrogen atoms in a discharge are determined. Recommendations are given to reduce the amount of impurities at the initial stage of discharge.

Further investigations of charge exchange and electron detachment - I. Ion energies 3 to 40 keV - II. Ion energies 100 to 4000 eV

1955 ◽  
Vol 227 (1171) ◽  
pp. 466-486 ◽  
Keyword(s):  
Charge Transfer ◽  
Energy Range ◽  
Cross Sections ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Hydrogen Ions ◽  
Electron Detachment ◽  
Rare Gases ◽  
Helium Ions ◽  
Ion Energies

This paper describes the measurement of charge transfer cross-sections for protons, molecular hydrogen ions and helium ions in the rare gases and hydrogen, and electron detachment cross-sections for negative atomic hydrogen ions in the rare gases. Part I describes the energy range 3 to 40 keV. In part II the energy range 100 to 4000 eV is described, and the results are discussed in terms of the pseudo-adiabatic hypothesis. Comparisons are made with other experimental results, and anomalous molecular cases are discussed in terms of reactions involving anti-bonding states.

Photodissociation of H2 near Threshold Energies

1970 ◽  
Vol 25 (2) ◽  
pp. 237-242 ◽  
Author(s):  
F. J. Comes ◽  
U. Wenning
Keyword(s):  
Electric Field ◽  
Cross Section ◽  
Configuration Interaction ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Hydrogen Atoms ◽  
Dissociation Cross Section ◽  
Excited Molecules ◽  
Threshold Energies ◽  
Near Threshold

Abstract Measurements of the atomic hydrogen fluorescence (Lyα) yield important information on the dissociation behavior of molecular hydrogen under photon impact. Under certain assumptions the dissociation cross section of the molecule can be deduced from such experiments. By applying an appropriate electric field in the observation region those dissociations leading to the formation of metastable hydrogen atoms can be quantitatively determined. This information opens the possibility to describe the predissociation of the excited H2-molecules in the C-, D-and B″-states. The experiments show that the excited molecules in these particular states dissociate into H(1S) and H(2S) by configuration interaction with the B′-state.

scholarly journals Production of atomic hydrogen by cosmic rays in dark clouds

2018 ◽  
Vol 619 ◽  
pp. A144 ◽  
Author(s):  
Marco Padovani ◽  
Daniele Galli ◽  
Alexei V. Ivlev ◽  
Paola Caselli ◽  
Andrea Ferrara
Keyword(s):  
Cosmic Rays ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Molecular Clouds ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Dissociation Rate ◽  
Low Energy ◽  
Hydrogen Atoms ◽  
Dark Clouds

Context. Small amounts of atomic hydrogen, detected as absorption dips in the 21 cm line spectrum, are a well-known characteristic of dark clouds. The abundance of hydrogen atoms measured in the densest regions of molecular clouds can only be explained by the dissociation of H2 by cosmic rays. Aims. We wish to assess the role of Galactic cosmic rays in the formation of atomic hydrogen, for which we use recent developments in the characterisation of the low-energy spectra of cosmic rays and advances in the modelling of their propagation in molecular clouds. Methods. We modelled the attenuation of the interstellar cosmic rays that enter a cloud and computed the dissociation rate of molecular hydrogen that is due to collisions with cosmic-ray protons and electrons as well as fast hydrogen atoms. We compared our results with the available observations. Results. The cosmic-ray dissociation rate is entirely determined by secondary electrons produced in primary ionisation collisions. These secondary particles constitute the only source of atomic hydrogen at column densities above ~1021 cm−2. We also find that the dissociation rate decreases with column density, while the ratio between the dissociation and ionisation rates varies between about 0.6 and 0.7. From comparison with observations, we conclude that a relatively flat spectrum of interstellar cosmic-ray protons, such as suggested by the most recent Voyager 1 data, can only provide a lower bound for the observed atomic hydrogen fraction. An enhanced spectrum of low-energy protons is needed to explain most of the observations. Conclusions. Our findings show that a careful description of molecular hydrogen dissociation by cosmic rays can explain the abundance of atomic hydrogen in dark clouds. An accurate characterisation of this process at high densities is crucial for understanding the chemical evolution of star-forming regions.

Catalytic Forming Gas Anneal on III-V/Ge MOS Systems

2009 ◽  
Vol 1194 ◽  
Author(s):  
Wei-E Wang ◽  
Han-Chung Lin ◽  
Guy Brammertz ◽  
Annelies Delabie ◽  
eddy simoen ◽  
...  
Keyword(s):  
Dielectric Layer ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Hydrogen Passivation ◽  
Hydrogen Atoms ◽  
Metal Gate ◽  
Interfacial Defects ◽  
Catalytic Metal ◽  
Lattice Matched

AbstractCatalytic-FGA, a combination of the standard forming gas anneal with a catalytic metal gate, has been applied to study the hydrogen passivation of III-V/Ge MOS systems. Pd (or Pt) metal gate catalytically dissociates molecular hydrogen into atomic hydrogen atoms, which then diffuse through the dielectric layer and neutralize certain semiconductor/dielectric interfacial defects. MOS systems with various interfacial qualities, including lattice-matched (n/p) In0.53Ga0.47As/10nm ALD-Al2O3 (or ZrO2)/Pd capacitors, an undoped Ge/˜1nm GeO2/4nm ALD-Al2O3/Pt capacitor, and an nGe/8nm ALD-Al2O3/Pt capacitor are fabricated to evaluate the effectiveness of C-FGA.

scholarly journals The Interaction of Hydrogen with Actinide Dioxide (111) Surfaces

2019 ◽  
Author(s):  
James Pegg ◽  
Ashley E. Shields ◽  
Mark T. Storr ◽  
David Scanlon ◽  
Nora De Leeuw
Keyword(s):  
Charge Distribution ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Hydrogen Adsorption ◽  
Hydroxyl Group ◽  
Spin Orbit ◽  
Hydrogen Ions ◽  
Cell Method ◽  
Spin Orbit Interactions ◽  
Thermodynamic Factors

The interaction of atomic and molecular hydrogen with the actinide dioxide (AnO<sub>2</sub>, An = U, Np, Pu) (111) surfaces has been investigated by DFT+U, where noncollinear 3k antiferromagnetic (AFM) behaviour and spin-orbit interactions (SOI) are considered. The adsorption of atomic hydrogen forms a hydroxide group, and is coupled to the reduction of an actinide ion. The energy of atomic hydrogen adsorption on the UO<sub>2</sub> (0.82 eV), NpO<sub>2</sub> (-0.10 eV), and PuO<sub>2</sub> (-1.25 eV) surfaces has been calculated. The dissociation of molecular hydrogen is not observed, and shown to be due to kinetic rather than thermodynamic factors. As a barrier in the formation of a second hydroxyl group, an unusual charge distribution has been shown. This is possibly a limitation of a (1·1) unit cell method. The recombination of hydrogen ions on the AnO<sub>2</sub> (111) surfaces is favoured over hydroxide formation.

scholarly journals Estimates of non-thermal atmospheric loss of exoplanet GJ 436b due to dissociation processes H2

2021 ◽  
Author(s):  
A. A. Avtaeva ◽  
◽  
V. I. Shematovich ◽  
◽  
Keyword(s):  
Energy Spectrum ◽  
Kinetic Energy ◽  
Uv Radiation ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Upper Atmosphere ◽  
Hydrogen Atoms ◽  
Thermal Escape ◽  
Atmospheric Loss

The contribution of the processes of dissociation of molecular hydrogen by hard ultraviolet (UV) radiation and the accompanying flux of photoelectrons to the formation of the fraction of suprathermal atomic hydrogen in the transition H2 −→ H region and the formation of the non-thermal escape flux from the extended upper atmosphere of the exoplanet — hot neptune GJ 436b — is estimated. The rate of formation and the energy spectrum of hydrogen atoms formed with an excess of kinetic energy during the dissociation of H2 are calculated.

Fast In-diffusion of Hydrogen at the Initial Stage of Hydrogen Plasma Treatment on a-Si:H Films Observed by In-situ ESR Measurements

2000 ◽  
Vol 609 ◽  
Author(s):  
Ujjwal Kr. Das ◽  
Tetsuji Yasuda ◽  
Satoshi Yamasaki
Keyword(s):  
Diffusion Coefficient ◽  
Atomic Hydrogen ◽  
Hydrogen Plasma ◽  
Hydrogen Treatment ◽  
Initial Stage ◽  
Lower Treatment ◽  
Spin Resonance ◽  
High Diffusion Coefficient ◽  
Diffusion Of Hydrogen

ABSTRACTTime evolution of Si dangling bonds (dbs) was monitored during atomic hydrogen treatment of a-Si:H films using an in-situ electron-spin-resonance (ESR) technique. A high diffusion coefficient (>10−10 cm2s−1) of free atomic H in a-Si:H was detected at the very initial stage of H exposure. Atomic H diffuses into the bulk of the film (∼100 nm) and creates additional metastable dbs. The spatial distribution of such metastable dbs becomes deeper at lower treatment temperatures. An activated type of db creation reaction determines the distribution of these dbs.

Raman investigation of hydrogen-implanted and DC hydrogen-plasma-treated Cz Si wafers

2009 ◽  
Vol 87 (4) ◽  
pp. 369-375
Author(s):  
A. M. Saad
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Molecular Hydrogen ◽  
Hydrogen Plasma ◽  
Defect Layer ◽  
Hydrogen Ions ◽  
Dc Plasma ◽  
Hydrogen Implantation ◽  
General Goal ◽  
Different Doses

The general goal of this work is to demonstrate that the buried defect layer created by hydrogen implantation can serve as a gettering region for hydrogen introduced from a DC plasma and to study the efficiency of this gettering affected by the implantation regimes. Standard n-type 4.5 Ω⋅cm Cz Si wafers were implanted by hydrogen ions with an energy of 100 keV and different doses of 1 × 1014, 1 × 1015, or 5 × 1015 atoms/cm2 at temperatures of 150, 300, 400, or 500 °C. After implantation, hydrogen was introduced to the wafers from the DC plasma at 150 °C. For a comparative estimation of the hydrogen concentration in the wafers implanted in different regimes Raman spectroscopy was used. The peaks of the Raman spectra associated with molecular hydrogen (H2), vacancy-hydrogen (V–H), and silicon–hydrogen (Si–H) complexes were studied depending on the implantation conditions. It is demonstrated that peaks of Raman spectra depend significantly on the dose and temperature of implantation. This means that the concentration of hydrogen in the wafers could be determined from the concentration and type of defects formed by hydrogen implantation. Maximum peaks associated with H2, Si–H, and V–H complexes were observed for the samples implanted at a temperature of 500 °C.

THE REACTION OF NITROGEN ATOMS WITH HYDROGEN ATOMS

1962 ◽  
Vol 40 (2) ◽  
pp. 240-245 ◽  
Author(s):  
C. Mavroyannis ◽  
C. A. Winkler
Keyword(s):  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Pressure Range ◽  
Flow System ◽  
Hydrogen Bromide ◽  
Hydrogen Atoms ◽  
Active Nitrogen ◽  
Reaction Tube ◽  
Fast Flow ◽  
Hydrogen Stream

The reaction has been studied in a fast-flow system by the addition of atomic hydrogen to active nitrogen. Hydrogen atom concentrations were estimated from the maximum destruction of hydrogen bromide in the atomic hydrogen stream. The nitrogen atom consumption, in the reaction mixture, was determined by addition of nitric oxide at different positions along the reaction tube. A lower limit of 4.87 ± 0.8 × 1014 cc2mole−2sec−1 was derived for the rate constant of the reaction of nitrogen atoms with hydrogen atoms, over the pressure range 2.5 to 4.5 mm, in an unheated reaction tube, poisoned with phosphoric acid. No reaction between nitrogen atoms and molecular hydrogen was observed, even at 350 °C.

scholarly journals Interaction of Hydrogen with Actinide Dioxide (111) Surfaces

2019 ◽  
Author(s):  
James Pegg ◽  
Ashley E. Shields ◽  
Mark T. Storr ◽  
David Scanlon ◽  
Nora De Leeuw
Keyword(s):  
Charge Distribution ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Hydrogen Adsorption ◽  
Hydroxyl Group ◽  
Spin Orbit ◽  
Hydrogen Ions ◽  
Cell Method ◽  
Spin Orbit Interactions ◽  
Thermodynamic Factors

The interaction of atomic and molecular hydrogen with the actinide dioxide (AnO<sub>2</sub>, An = U, Np, Pu) (111) surfaces has been investigated by DFT+U, where noncollinear 3k antiferromagnetic (AFM) behaviour and spin-orbit interactions (SOI) are considered. The adsorption of atomic hydrogen forms a hydroxide group, and is coupled to the reduction of an actinide ion. The energy of atomic hydrogen adsorption on the UO<sub>2</sub> (0.82 eV), NpO<sub>2</sub> (-0.10 eV), and PuO<sub>2</sub> (-1.25 eV) surfaces has been calculated. The dissociation of molecular hydrogen is not observed, and shown to be due to kinetic rather than thermodynamic factors. As a barrier in the formation of a second hydroxyl group, an unusual charge distribution has been shown. This is possibly a limitation of a (1·1) unit cell method. The recombination of hydrogen ions on the AnO<sub>2</sub> (111) surfaces is favoured over hydroxide formation.

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