scholarly journals UV Enhancement of Surface Catalytic Polymerization of Ethylene

1988 ◽  
Vol 129 ◽  
Author(s):  
Parul Vora Purohit ◽  
Mordechai Rothschild ◽  
Daniel J. Ehrlich
Keyword(s):  
Thin Film ◽  
Fourier Transform ◽  
Gas Phase ◽  
Solid Phase ◽  
Catalytic Polymerization ◽  
Saturation Thickness ◽  
Partial Pressures ◽  
Rate Of Polymerization ◽  
Phase Chemical

ABSTRACTThe polymerization of ethylene on surfaces sequentially dosed with TiC14 and trimethylaluminum was studied by Fourier transform infrared spectroscopy. The polymer film was observed in situ as a function of time and under the influence of 254-nm cw radiation. The rate of polymerization and the saturation thickness of the polyethylene are strongly dependent on the order of dosing and the partial pressures of the reactants that form the catalyst. UV enhancement of polymerization was demonstrated to occur through two separate photochemical channels: gas-phase photolysis of the reactants and solid-phase chemical transformation of a noncatalytic thin film.

Hydrogen concentrations in methane-forming cells probed by the ratios of reduced and oxidized coenzyme F420

Microbiology ◽  
2005 ◽  
Vol 151 (5) ◽  
pp. 1697-1705 ◽  
Author(s):  
Linda M. I. de Poorter ◽  
Wim J. Geerts ◽  
Jan T. Keltjens
Keyword(s):  
Gas Phase ◽  
Thermodynamic Equilibrium ◽  
Standard Free Energy ◽  
Methanosarcina Barkeri ◽  
Standard Free Energy Change ◽  
Partial Pressures ◽  
Batch Fermenter ◽  
Dissolved Hydrogen ◽  
Methanothermobacter Thermautotrophicus

Coenzyme F420 is the central low-redox-potential electron carrier in methanogenic metabolism. The coenzyme is reduced under hydrogen by the action of F420-dependent hydrogenase. The standard free-energy change at pH 7 of F420 reduction was determined to be −15 kJ mol−1, irrespective of the temperature (25–65 °C). Experiments performed with methane-forming cell suspensions of Methanothermobacter thermautotrophicus incubated under various conditions demonstrated that the ratios of reduced and oxidized F420 were in thermodynamic equilibrium with the gas-phase hydrogen partial pressures. During growth in a fed-batch fermenter, ratios changed in connection with the decrease in dissolved hydrogen. For most of the time, the changes were as expected for thermodynamic equilibrium between the oxidation state of F420 inside the cells and extracellular hydrogen. Also, methanol-metabolizing, but not acetate-converting, cells of Methanosarcina barkeri maintained the ratios of reduced and oxidized coenzyme F420 in thermodynamic equilibrium with external hydrogen. The results of the study demonstrate that F420 is a useful probe to assess in situ hydrogen concentrations in H2-metabolizing methanogens.

scholarly journals Fourier-transform spectral interferometry for in situ group delay dispersion monitoring of thin film coating processes

2016 ◽  
Vol 24 (20) ◽  
pp. 22516 ◽  
Author(s):  
Sebastian Schlichting ◽  
Thomas Willemsen ◽  
Henrik Ehlers ◽  
Uwe Morgner ◽  
Detlev Ristau
Keyword(s):  
Thin Film ◽  
Fourier Transform ◽  
Group Delay ◽  
Film Coating ◽  
Group Delay Dispersion ◽  
Thin Film Coating ◽  
Spectral Interferometry

scholarly journals FORMATION OF MG2SI THIN FILMS ON SI (111) AND THEIR RESEARCH BY EOS AND EELS

2021 ◽  
pp. 30-34
Author(s):  
DMITRIY VLADIMIROVICH FOMIN ◽  
◽  
NIKITA SERGEEVICH NOVGORODTSEV ◽  
DMITRIY OLEGOVICH STRUKOV ◽  
ALEXEY VYACHESLAVOVICH POLYAKOV ◽  
...  
Keyword(s):  
Thin Film ◽  
Vacuum Chamber ◽  
Solid Phase ◽  
Auger Spectroscopy ◽  
Magnesium Silicide ◽  
Characteristic Energy ◽  
Electron Auger Spectroscopy ◽  
High Vapor ◽  
Electron Auger

The paper presents information on the results of the formation of a thin Mg2Si film on a silicon substrate by solid-phase epitaxy in an ultrahigh-vacuum chamber of the PHI model 590 device. There are a number of difficulties in the formation of magnesium silicide films due to the low condensation coefficient and high vapor pressure. Effective methods for the formation of Mg2Si are currently being sought. As a result of our experiment, a thin film was obtained, which was studied in-situ by the method of electron Auger spectroscopy and spectroscopy of characteristic energy losses by electrons. Analysis of the Auger electron spectrum showed the presence of magnesium and silicon atoms in the composition of the formed film. From the analysis of the EELS spectra, it was found that a thin film of silicide magnesium was formed.

Thin film transistors fabricated by in situ doped unhydrogenated polysilicon films obtained by solid phase crystallization

2001 ◽  
Vol 16 (11) ◽  
pp. 918-924 ◽  
Author(s):  
L Pichon ◽  
K Mourgues ◽  
F Raoult ◽  
T Mohammed-Brahim ◽  
K Kis-Sion ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Solid Phase ◽  
Solid Phase Crystallization ◽  
Polysilicon Films

Photopolymerization Dynamics Studies of Acrolein on Al, Ni, and Au Substrates Using Surface Second Harmonic Generation

1995 ◽  
Vol 385 ◽  
Author(s):  
Fang Chen ◽  
Suchitra Subrahmanyan ◽  
Hilary S. Lackritz
Keyword(s):  
Vapor Pressure ◽  
Second Harmonic Generation ◽  
Real Time ◽  
Gas Phase ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Dark Reaction ◽  
Pressure Decay ◽  
Rate Of Polymerization

ABSTRACTThe dynamics of the gas phase photopolymerization of acrolein on aluminum (Al), nickel (Ni), and gold (Au) substrates were studied in-situ and in real time using surface second harmonic generation (SSHG) and monitoring vapor pressure decay. The Al and Ni substrates had a significant effect on the apparent rate of polymerization. A dark reaction after irradiation occurred in the absence of metal (Al or Ni) substrates, but no dark reaction was observed when the metal substrates were present. The significant differences in the metal/monomer interactions during photopolymerization are indicated by SEMs of the polyacrolein, as well as evidence from FTIR-ATR spectra. The SSHG intensities from the Au, Al, and polyacrolein surfaces were obtained.

Eqilibrium Analysis of the TMGa-TMA1-AsH3-H2 Mocvd Epitaxial Growth System

1988 ◽  
Vol 131 ◽  
Author(s):  
Hyuk J. Moon ◽  
Thomas G. Stoebe ◽  
Brian K. Chadwick
Keyword(s):  
Gas Phase ◽  
Solid Phase ◽  
Total System ◽  
Method Of Calculation ◽  
System Pressure ◽  
Partial Pressures ◽  
Growth System ◽  
Effects Of Temperature ◽  
Temperature And Pressure ◽  
Thermodynamic Equilibrium State

ABSTRACTThe thermodynamic equilibrium state of the Ga-Al-As-C-H system was determined theoretically by means of an iterative equilibrium constant method. This method of calculation is presented and discussed. With very little operator input, the program is capable of computing the partial pressures of the gas-phase species present in the equilibrated system.In these calculations the system was considered to be saturated with solid-phase A1GaAs and included 58 plausible gas-phase intermediates which evolved from the initially present gas species; trimethylgallium, trimethylaluminum, arsine, and hydrogen. Temperature and total system pressure ranges investigated were 750–1100 K and 0.1 atm-1.0 atm, respectively. The effects of temperature and pressure variations, in addition to effects caused by changes in the appropriate atom ratios, have been delineated. The properties of this equilibrated system are compared with those from recent thermodynamic research efforts on AlGaAs systems consisting of only gaseous constituents.

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