The effects of incorporating water into vacuum-deposited amorphous silicon films

1986 ◽  
Vol 64 (1) ◽  
pp. 16-21 ◽  
Author(s):  
R. Audas ◽  
D. E. Brodie ◽  
J. A. Cowan ◽  
C. J. L. Moore
Keyword(s):  
Partial Pressure ◽  
Water Vapour ◽  
Low Energy ◽  
Room Temperature Resistivity ◽  
Film Properties ◽  
Low Energy Electrons ◽  
Ambient Gases ◽  
Low Energy Electron ◽  
Temperature Resistivity

This paper describes the effects on some of the electrical and optical properties of a-Si: C films prepared by vacuum deposition in controlled ambient gases of N2, O2, H2, and water vapour. This stidy was initiated in an attempt to determine the role of a low-energy electron beam irradiating the substrate and film as the layer grows. We find that depositing an a-Si:C film in a water-vapour environment, at a partial pressure of only 4 × 10−8 Torr, will result in the film having a room-temperature resistivity two thousand times higher than that for "clean" films deposited in a good vacuum with a partial pressure of water vapour near 4 × 10−9 Torr (1 Torr = 133.3 Pa). If the partial pressure of the water vapour is increased, the film resistivity increases and it becomes photoconducting. By comparison, the other gases tested had no measurable effect on the properties of the films, with the exception of oxygen which increases the film resistance. None of these latter films were photoconducting. We conclude that the improvement observed in the film properties when samples are irradiated with low-energy electrons results more from the effects of water vapour and (or) oxygen which can be freed from cold surfaces near the substrate than from a possible restructuring of the film as postulated earlier (1).

The role of an energy-dependent inner potential in quantitative low-energy electron diffraction

2000 ◽  
Vol 458 (1-3) ◽  
pp. 155-161 ◽  
Author(s):  
S Walter ◽  
V Blum ◽  
L Hammer ◽  
S Müller ◽  
K Heinz ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Low Energy ◽  
Energy Electron ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Energy Dependent

Oxidising Role of Water Vapour in the 250 Kev D+ Induced Radiolysis of Polyimide Kapton-H

1988 ◽  
Vol 100 ◽  
Author(s):  
U. K. Chaturvedi ◽  
A. Patnaik ◽  
Ramji Pathak ◽  
R. N. Chakraborty ◽  
A. K. Nigam
Keyword(s):  
Partial Pressure ◽  
Water Vapour ◽  
Ion Beam ◽  
Adsorbed Water ◽  
Vacuum System ◽  
Residual Water ◽  
Implantation Time ◽  
Polymeric Surface ◽  
Imide Ring

Residual water vapour present in the vacuum system has been observed to play a dominant oxidising role in the 250 keV D+ induced radiolysis of polyimide (Kapton-H). The partial pressure (pp) of water in the vacuum system decreases sharply as the D+ beam impinges the polymeric surface, but soon after, it recovers to its initial value as the accumulated dose increases. Emission of CO2 is observed which has its maximum at a time when the H2O partial pressure is at a minimum. The CO2 level also returns to its original level with time. This complementary variation of CO2 and H2O confirms that absorbed and adsorbed water molecules are radiolysed by the ion beam and initiate oxidation of the radiolytically evolved CO to yield CO2 on and within the ion implanted surface of the polyimide. Further, the small enhancement in the 28 amu peak (N2 + CO), which exhibits no maximum/minimum over the entire implantation time, can be understood in terms of the evolution of N2 from the imide ring as a result of radiolysis of this nitrogen containing polymers.

Growth of Epitaxial Co Layers on Sb-Passivated GaAs(110) Substrates

1998 ◽  
Vol 05 (01) ◽  
pp. 279-283 ◽  
Author(s):  
C. M. Teodorescu ◽  
J. Chrost ◽  
H. Ascolani ◽  
J. Avila ◽  
F. Soria ◽  
...  
Keyword(s):  
Polar Angle ◽  
Low Energy ◽  
Photoelectron Diffraction ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
A Minor ◽  
Bcc Phase ◽  
Crystallographic Axes

The role of Sb in the formation of the Co/GaAs(110) interfaces has been investigated by angular photoelectron diffraction (PD), synchrotron-radiation (SR) core-level photoemission and low-energy electron diffraction. We find that Co forms a metastable bcc phase on GaAs(110), with its principal crystallographic axes parallel to the substrate. From polar-angle-scanned PD, we determine an outward expansion of up to 14% of the lattice constant perpendicular to the surface, for epitaxial Co films grown on nontreated substrates. By Sb passivation of the GaAs(110) surface prior to the Co deposition, the epitaxial quality of the metallic overlayer is improved. The resulting Co phase is found to grow in a perfect bcc (110) orientation with a minor disruption of the substrate underneath and a reduced intralayer spacing outward expansion of less than 1%.

POSSIBLE "HOT" MOLECULE DESORPTION BY ELECTRON STIMULATED DECOMPOSITION OF DIHALOETHANES ON Cu(111)

1994 ◽  
Vol 01 (04) ◽  
pp. 535-538 ◽  
Author(s):  
S. TURTON ◽  
M. KADODWALA ◽  
ROBERT G. JONES
Keyword(s):  
Electron Capture ◽  
Photoelectron Spectroscopy ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Negative Ions ◽  
Low Energy ◽  
First Order ◽  
Sufficient Energy ◽  
Low Energy Electrons ◽  
Low Energy Electron

The desorption of ethene from physisorbed 1, 2-dichloroethane (DCE) and 1-bromo-2-chloroethane (BCE) on Cu(111) has been observed on irradiating the surface with electrons. The techniques used were low energy electron diffraction (LEED), Auger electron spectroscopy (AES), ultraviolet photoelectron spectroscopy (UPS), and mass spectrometric detection of the desorbed species. At 110 K physisorbed DCE and BCE underwent electron capture from low energy (<1 eV ) electrons in the secondary electron yield of the surface followed by decomposition and desorption of ethene alone. The decomposition was found to be first order in the surface coverage of the physisorbed DCE/BCE. No other molecular species desorbed from the surface, a stoichiometric amount of chemisorbed halogen was deposited and no carbon was detectable at the end of the desorption. The formation of the negative ions of these molecules by electron capture of low energy electrons in the secondary electron emission from the surface and the possible dynamics by which the negative ions undergo decomposition leaving the ethene product with sufficient energy to desorb, are discussed.

HgCl B2Σ+1/2 formation by low-energy electron impact dissociation of HgCl2 and(or) CH3HgCl molecules: applications to HgCl (B → X) laser

1990 ◽  
Vol 68 (2) ◽  
pp. 166-169 ◽  
Author(s):  
Mohammad F. Mahmood
Keyword(s):  
Energy Range ◽  
Electron Energy ◽  
Cross Sections ◽  
Band System ◽  
Low Energy ◽  
Dissociative Excitation ◽  
Intense Band ◽  
Electron Impact Dissociation ◽  
Low Energy Electrons ◽  
Low Energy Electron

An investigation was made of the process of dissociative excitation of a HgCl radical in the B2Σ+1/2 state due to collisions of low-energy electrons with HgCl2 and CH3HgCl molecules. Using the most intense band of the B2Σ+1/2 – X2Σ+1/2 system of the HgCl radical at 557 nm that corresponds to the ν′ = 0 to ν″ = 22 transition, emission cross sections were measured in the electron energy range 1–100 eV. The threshold electron energy for the observation of the B2Σ+1/2 – X2Σ+1/2 band system has been determined to be 7.0 and 8.0 eV for HgCl2 and CH3HgCl molecules, respectively.

scholarly journals 5-Nitro-2,4-Dichloropyrimidine as an Universal Model for Low-Energy Electron Processes Relevant for Radiosensitization

2020 ◽  
Vol 21 (21) ◽  
pp. 8173
Author(s):  
Thomas F. M. Luxford ◽  
Stanislav A. Pshenichnyuk ◽  
Nail L. Asfandiarov ◽  
Tomáš Perečko ◽  
Martin Falk ◽  
...  
Keyword(s):  
Rational Design ◽  
Electron Attachment ◽  
Low Energy ◽  
Energy Electron ◽  
Model Molecule ◽  
Alternative Approach ◽  
Low Energy Electrons ◽  
Cluster Environment ◽  
Low Energy Electron ◽  
Low Solubility

We report experimental results of low-energy electron interactions with 5-nitro-2,4-dichloropyrimidine isolated in the gas phase and hydrated in a cluster environment. The molecule exhibits a very rare combination of many so far hypothesized low-energy electron induced mechanisms, which may be responsible for synergism in concurrent chemo-radiation therapy of cancer. In contrast to many previous efforts to design an ideal radiosensitizer based on one mode of action, the present model molecule presents an alternative approach, where several modes of action are combined. With respect to the processes induced by the low-energy electrons, this is not a trivial task because of strong bond specificity of the dissociative electron attachment reaction, as it is discussed in the present paper. Unfortunately, low solubility and high toxicity of the molecule, as obtained from preliminary MTT assay tests, do not enable further studies of its activity in real biological systems but it can advantageously serve as a model or a base for rational design of radiosensitizers.

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