Surface Luminescence of Polycrystalline Zinc Oxide Excited by Hydrogen Atoms

2006 ◽  
Vol 957 ◽  
Author(s):  
Michael Sushchikh ◽  
Vladislav Styrov ◽  
Vladimir Tyutunnikov ◽  
Nick Cordella
Keyword(s):  
Atomic Hydrogen ◽  
Hydrogen Atmosphere ◽  
Adsorbed Hydrogen ◽  
Hydrogen Atoms ◽  
Long Wavelength ◽  
Pl Spectra ◽  
Zno Powders ◽  
Exothermic Chemical Reaction ◽  
Heterogeneous Chemiluminescence ◽  
Surface Luminescence

ABSTRACTExcitation of a luminescence by highly exothermic chemical reaction on the surface of a luminophore provides a unique opportunity to separate surface luminescence from the bulk luminescence. This enables studies of the electronic properties of the semiconductor surfaces even if the surfaces are of complicate shapes. We have studied heterogeneous chemiluminescence (HCL) of ZnO powders. The luminescence was excited by a release of chemical energy, namely by catalytic recombination of hydrogen atoms. The HCL spectra were compared to the photoluminescence (PL) spectra. The HCL spectra were sensitive to the details of preparation and treatment whereas PL spectra almost did not change. HCL spectra of powder samples pretreated for enhancing “green” luminescence exhibited long-wavelength tail (up to 800 nm) and their maximum was blue-shifted as compared with PL spectra. Different HCL bands forming long-wavelength tail were isolated by changing the temperature of the samples. Additional milling of ZnO led to amplification of the HCL-specific surface bands. Pure ZnO showed neither PL nor HCL; however we were able to observe HCL surface bands with maxima at 610 nm and 730 nm after treatment of the sample in atomic hydrogen atmosphere at 570 K. Remarkably, such treatment did not cause appearance of the PL. The HCL in the presence of atomic hydrogen was steady in time and was caused by an abstraction of adsorbed hydrogen by incident hydrogen atoms, i.e. the reaction followed Eley-Rideal mechanism. The HCL can be utilized for in situ monitoring of the growth and evolution of ZnO in controlled atmosphere.

Effect of Atomic Hydrogen Concentration in the Study of Adsorption on Graphene

2011 ◽  
Vol 465 ◽  
pp. 211-214
Author(s):  
A.V. Pak ◽  
Nikolay G. Lebedev
Keyword(s):  
Band Structure ◽  
Russian Federation ◽  
Atomic Hydrogen ◽  
Function Method ◽  
Hydrogen Adsorption ◽  
Adsorbed Hydrogen ◽  
Hydrogen Atoms ◽  
Statistical Research ◽  
Graphene Surface ◽  
Quantum Statistical

The results of theoretical quantum-statistical research of atomic hydrogen adsorption on the graphene surface within the framework of the periodic Anderson’s model have been presented. The band structure of graphene with adsorbed hydrogen atoms is calculated by the Green's function method. The work is supported by The Education Ministry of Russian Federation (project No. NK-16(3)).

The State of Hydrogen Desorbing from Intermediates Formed by Ammonia Interaction with Tungsten Surfaces

1974 ◽  
Vol 52 (7) ◽  
pp. 1147-1154 ◽  
Author(s):  
Y. K. Peng ◽  
P. T. Dawson
Keyword(s):  
Hydrogen Atom ◽  
Atomic Hydrogen ◽  
Surface Concentration ◽  
Hydrogen Desorption ◽  
Pure Hydrogen ◽  
Adsorbed Hydrogen ◽  
Tungsten Filament ◽  
Hydrogen Atoms ◽  
Ionization Source ◽  
Hydrogen Desorbing

Ammonia interaction with a tungsten surface can generate dense adlayers containing nitrogen and hydrogen, i.e. an η-species of surface stoichiometry Ws2N3H. In thermal desorption mass spectrometry experiments, hydrogen desorbing from the η-species interacts with the glass wall in a manner similar to that previously observed for atomic hydrogen. This paper describes two mass spectrometric techniques designed to confirm this conclusion directly. The first method uses a line-of-sight geometry between the tungsten filament and the ionization source of the mass spectrometer and the results indicate that, at least, part of the hydrogen desorbing from the η-species does so atomically. In the second method a multiple wall collision geometry is used but prior saturation of the wall with D atoms will result in an HD+ ion current for desorbing H atoms. The results suggest that 26% of the hydrogen desorbs atomically. Hydrogen atom desorption from the η-species occurs at tungsten filament temperatures below those required for hydrogen atom evaporation from a pure hydrogen adlayer. It is proposed that a reduced binding energy for adsorbed hydrogen atoms and a reduced mobility of these adatoms arises from the presence of a large surface concentration of nitrogen. This will result in the rates of atomic hydrogen desorption and bimolecular recombination becoming comparable at temperatures lower than is the case for pure hydrogen interaction with tungsten. The implications of these results for the ammonia synthesis reaction are discussed.

Low-Temperature Post-Oxidation Annealing Using Atomic Hydrogen Radicals Generated by High-Temperature Catalyzer for Improvement in Reliability of Thermal Oxides on 4H-SiC

2006 ◽  
Vol 527-529 ◽  
pp. 999-1002
Author(s):  
Junji Senzaki ◽  
Atsushi Shimozato ◽  
Kenji Fukuda
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Atomic Hydrogen ◽  
High Reliability ◽  
Hydrogen Atmosphere ◽  
Exposed Sample ◽  
New Apparatus ◽  
Hydrogen Radical ◽  
Hydrogen Radicals ◽  
Sic Wafer

Low-temperature post-oxidation annealing (POA) process of high-reliability thermal oxides grown on 4H-SiC using new apparatus that generates atomic hydrogen radicals by high-temperature catalyzer has been investigated. Atomic hydrogen radicals were generated by thermal decomposition of H2 gas at the catalyzer surface heated at high temperature of 1800°C, and then exposed to the sample at 500°C in reactor pressure of 20 Pa. The mode and maximum values of field-to-breakdown are 11.0 and 11.2 MV/cm, respectively, for the atomic hydrogen radical exposed sample. In addition, the charge-to-breakdown at 63% cumulative failure of the thermal oxides for atomic hydrogen radical exposed sample was 0.51 C/cm2, which was higher than that annealed at 800°C in hydrogen atmosphere (0.39 C/cm2). Consequently, the atomic hydrogen radical exposure at 500°C has remarkably improved the reliability of thermal oxides on 4H-SiC wafer, and is the same effect with high-temperature hydrogen POA at 800°C.

scholarly journals Сечения образования ионов He-=SUP=-+-=/SUP=- в различных электронных состояниях при столкновениях ионов He-=SUP=-2+-=/SUP=- с атомами водорода

2020 ◽  
Vol 90 (6) ◽  
pp. 895
Author(s):  
А.А. Басалаев ◽  
В.В. Кузьмичев ◽  
М.Н. Панов ◽  
О.В. Смирнов
Keyword(s):  
Kinetic Energy ◽  
Electron Capture ◽  
Cross Sections ◽  
Atomic Hydrogen ◽  
Precision Measurements ◽  
Capture Cross ◽  
Hydrogen Atoms ◽  
Hydrogen Target ◽  
Degree Of Dissociation ◽  
Capture Cross Sections

Using collision spectroscopy based on precision measurements of the kinetic energy of projectile ions that capture an electron, we measured the state selective electron capture cross sections of formation of He^+(n) ions at collision 3^He^{2 +} ions with an energy of E = 1.4-10 keV/a.m.u. with hydrogen atoms. The atomic hydrogen target with a degree of dissociation 78% at a temperature of tungsten dissociation cell 2180K has been made.

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.

Inactive step-edge Pt atoms boost oxygen reduction reaction by activating adsorbed hydrogen atoms

2020 ◽  
Vol 504 ◽  
pp. 144434 ◽  
Author(s):  
Na Cheng ◽  
Ling Zhang ◽  
Yuhang Li ◽  
Liyuan Chen ◽  
Hao Jiang ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reduction Reaction ◽  
Step Edge ◽  
Adsorbed Hydrogen ◽  
Hydrogen Atoms

Stationary inverted Lyman populations and free-free and bound-free emission of lower-energy state hydride ion formed by an exothermic catalytic reaction of atomic hydrogen and certain group I catalysts

Open Physics ◽  
2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Randell Mills ◽  
William Good ◽  
Peter Jansson ◽  
Jiliang He
Keyword(s):  
Catalytic Reaction ◽  
Atomic Hydrogen ◽  
Microwave Plasma ◽  
Energy State ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Hydrogen Atoms ◽  
Hydride Ion ◽  
Group I ◽  
Excess Power

AbstractRb+ to Rb2+ and 2K+ to K + K2+ each provide a reaction with a net enthalpy equal to the potential energy of atomic hydrogen. The presence of these gaseous ions with thermally dissociated hydrogen formed a plasma having strong VUV emission with a stationary inverted Lyman population. Significant Balmer α line broadening of 18 and 9 eV was observed from a rt-plasma of hydrogen with KNO3, and RbNO3, respectively, compared to 3 eV from a hydrogen microwave plasma. The reaction was exothermic since excess power of about 20 mW/cc was measured by Calvet calorimetry. We propose an energetic catalytic reaction involving a resonance energy transfer between hydrogen atoms and Rb+ or 2K+ to form a very stable novel hydride ion. Its predicted binding energy of 3.0471 eV with the fine structure was observed at 4071 Å, and its predicted bound-free hyperfine structure lines matched those observed for about 40 lines to within.01 percent. Characteristic emission from each catalyst was observed. This catalytic reaction may pump a CW HI laser.

Curve-crossing collisions of excited lead atoms in flames

1981 ◽  
Vol 376 (1767) ◽  
pp. 545-564 ◽  
Keyword(s):  
Rate Constant ◽  
Atomic Hydrogen ◽  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Model Systems ◽  
Attractive Potential ◽  
Hydrogen Atoms ◽  
Lennard Jones ◽  
Increasing Temperature ◽  
Curve Crossing

Lead atoms, present as a trace additive in a series of premixed H 2 –N 2 –O 2 flames, were excited to the 7 3 P o 1 state by 405.8 nm radiation from a nitrogen-pumped dye laser. Rate constants for spin-orbit relaxation to the 7 3 P o 0 state were obtained separately for collisions with atomic hydrogen and for collisions with the bulk flame gas, by measuring the relative intensities of fluorescence at 364.0 and 368.3 nm as a function of distance from the reaction zone in each flame. For hydrogen atoms the rate constant is typically 1 x 10 -9 cm 3 molecule -1 s -1 , decreasing with increasing temperature; for the bulk flame gas the rate constant is typically 1 x 10 -11 cm 3 molecule -1 s -1 , increasing with increasing temperature. Numerical calculations for model systems, with the use of Morse and Lennard-Jones potentials to describe the interaction of the colliding species, show that the negative temperature coefficient found for atomic hydrogen can be attributed to the crossing of attractive potential curves, corresponding to bound excited states of PbH.

scholarly journals Design of Transversal Phase Space Meter for Atomic Hydrogen Beam Source

2016 ◽  
Vol 40 ◽  
pp. 1660101
Author(s):  
A. S. Belov
Keyword(s):  
Phase Space ◽  
Atomic Beam ◽  
Atomic Hydrogen ◽  
Ion Beam ◽  
Longitudinal Velocity ◽  
Sensitive Detector ◽  
Hydrogen Atoms ◽  
Beam Source ◽  
Hydrogen Beam ◽  
Beam Technique

For optimization of polarized atomic beam sources apparatus it is important to have detailed information about characteristics of sources of hydrogen atoms, especially, taking into account present intensity limitations of polarized atomic beam sources. Usually, longitudinal velocity distribution of hydrogen atoms produced by RF dissociator is measured while transversal phase space of unpolarized atomic hydrogen beams was not measured up to now. In this work we report and discuss a design of transversal phase space meter for pulsed atomic hydrogen beam source. The meter design is based on “two slits” method which is well known from ion beam technique. Specific feature of the meter are movable sensitive detector of hydrogen atoms and molecules.

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