Chemical reactions of atomic hydrogen at SiC surface and heterogeneous chemiluminescence

2005 ◽  
Vol 66 (2-4) ◽  
pp. 513-520 ◽  
Author(s):  
V.V. Styrov ◽  
V.I. Tyutyunnikov ◽  
O.T. Sergeev ◽  
Y. Oya ◽  
K. Okuno
Keyword(s):  
Chemical Reactions ◽  
Atomic Hydrogen ◽  
Heterogeneous Chemiluminescence

Growth Kinetics for Propagation of Si-Network

1989 ◽  
Vol 149 ◽  
Author(s):  
M Azuma ◽  
H Shirai ◽  
J. Hanna ◽  
I Shimizu
Keyword(s):  
Chemical Reactions ◽  
Growth Kinetics ◽  
Atomic Hydrogen ◽  
Preliminary Analysis ◽  
Chemical Affinity ◽  
Effective Agent ◽  
Induced Decomposition ◽  
Kinetics Of

ABSTRACTChemical reactions were systematically investigated with regard to the propagation of Si-network in the vicinity of the growing surface by using various precursors, SiHn, SiHnFm, and SiHnCim (n+m≤3) generated by plasma-induced decomposition of SiH4, SiF4, SiH2Cl2 and SiHCl3. Atomic hydrogen was an effective agent to promote the propagation reaction due to its strong chemical affinity for silicon and its ability to diffuse through the Si-network. A preliminary analysis was made of the kinetics of the propagation reactions.

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.

Control of Chemical Reactions for Growth of Crystalline Si at Low Substrate Temperature

1989 ◽  
Vol 164 ◽  
Author(s):  
Isamu Shimizu ◽  
Jun-Ichi Hanna ◽  
Hajime Shirai
Keyword(s):  
Low Temperature ◽  
Substrate Temperature ◽  
Chemical Reactions ◽  
Systematic Study ◽  
Atomic Hydrogen ◽  
Network Structures ◽  
Control Of Flow ◽  
Selection Of

AbstractA systematic study has been made on the formation of Si-network of amorphous(a-), microcrystalline(μc-) and epitaxial (epi)-Si prepared by Plasma-Enhaced (PE-) CVD under control of flow of atomic hydrogen. The control of the Si-network structures requires a deliberate selection of the precursor, i.e., SiHn (n≤53) and SiFnHm (n+m≤53), as well as an intentional acceleration of the chemical reactions for the propagation of Si-network in the vicinity of the growing surface by impinging of atomic hydrogen. A plausible interpretation was given to the growing mechanism of c-Si at low temperature.

Surface reactions observed by photoemission electron microscopy (PEEM)

1992 ◽  
Vol 50 (1) ◽  
pp. 286-287
Author(s):  
H.H. Rotermund
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Work Function ◽  
Chemical Reactions ◽  
Reaction Diffusion ◽  
Dynamic Processes ◽  
Clean Surface ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Photoemission Electron

Chemical reactions at a surface will in most cases show a measurable influence on the work function of the clean surface. This change of the work function δφ can be used to image the local distributions of the investigated reaction,.if one of the reacting partners is adsorbed at the surface in form of islands of sufficient size (Δ>0.2μm). These can than be visualized via a photoemission electron microscope (PEEM). Changes of φ as low as 2 meV give already a change in the total intensity of a PEEM picture. To achieve reasonable contrast for an image several 10 meV of δφ are needed. Dynamic processes as surface diffusion of CO or O on single crystal surfaces as well as reaction / diffusion fronts have been observed in real time and space.

Microwaves: Application in Electron Microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 140-141
Author(s):  
Anthony S-Y Leong ◽  
David W Gove
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Chemical Reactions ◽  
Electromagnetic Waves ◽  
Tissue Fixation ◽  
Primary Method ◽  
Dipolar Molecules ◽  
Wide Range ◽  
Time Required ◽  
Cryostat Sections

Microwaves (MW) are electromagnetic waves which are commonly generated at a frequency of 2.45 GHz. When dipolar molecules such as water, the polar side chains of proteins and other molecules with an uneven distribution of electrical charge are exposed to such non-ionizing radiation, they oscillate through 180° at a rate of 2,450 million cycles/s. This rapid kinetic movement results in accelerated chemical reactions and produces instantaneous heat. MWs have recently been applied to a wide range of procedures for light microscopy. MWs generated by domestic ovens have been used as a primary method of tissue fixation, it has been applied to the various stages of tissue processing as well as to a wide variety of staining procedures. This use of MWs has not only resulted in drastic reductions in the time required for tissue fixation, processing and staining, but have also produced better cytologic images in cryostat sections, and more importantly, have resulted in better preservation of cellular antigens.

Sign in / Sign up

Export Citation Format

Share Document