scholarly journals Theoretical spectroscopic characterization at low temperatures of methyl hydroperoxide and three S-analogs

2015 ◽  
Vol 142 (7) ◽  
pp. 074304 ◽  
Author(s):  
S. Dalbouha ◽  
M. L. Senent ◽  
N. Komiha
Keyword(s):  
Low Temperatures ◽  
Spectroscopic Characterization ◽  
Methyl Hydroperoxide

The gaseous oxidation of acetone - II. The low-temperature reaction

1964 ◽  
Vol 279 (1377) ◽  
pp. 248-259 ◽  
Keyword(s):  
Low Temperature ◽  
Temperature Region ◽  
Low Temperatures ◽  
Peroxy Radical ◽  
Reaction Scheme ◽  
Methyl Radical ◽  
High Temperature Region ◽  
Region I ◽  
Methyl Hydroperoxide ◽  
Kinetics Of

The kinetics of the oxidation of acetone in the 'low-temperature’ region (i. e. below 320°C) have been carefully investigated. In contrast to the high-temperature region, the products include no methane, but appreciable quantities of methyl hydroperoxide as well as water, carbon monoxide and dioxide. A reaction scheme is suggested which involves degenerate chain branching by the homo­geneous decomposition of methyl hydroperoxide. The transition from the low-temperature mechanism to that prevailing at high tempera­tures is due to the changing importance of the alternative reactions of the methyl radical. At low temperatures, the formation of methyl hydroperoxide is favoured CH 3 + O 2 + M = CH 3 O 2 + M , CH 3 O 2 + R H = CH 3 O 2 H + R , whereas at high temperatures the methyl peroxy radical is too unstable to abstract hydro­gen and instead the reaction yields formaldehyde CH 3 + O 2 = HCHO + OH.

scholarly journals Theoretical spectroscopic characterization at low temperatures of S-methyl thioformate and O-methyl thioformate

2014 ◽  
Vol 141 (10) ◽  
pp. 104303 ◽  
Author(s):  
M. L. Senent ◽  
C. Puzzarini ◽  
M. Hochlaf ◽  
R. Domínguez-Gómez ◽  
M. Carvajal
Keyword(s):  
Low Temperatures ◽  
Spectroscopic Characterization

Methyl(trifluormethyl)haIogensulfonium-Salze [1] Halogen = F, CI, Br, I Methyl(trifluoromethyl)halosulfonium Salts [1] / Methyl(trifluoromethyl)halosulfonium Salts [1] Halogen = F, Cl, Br, I

1988 ◽  
Vol 43 (4) ◽  
pp. 403-411 ◽  
Author(s):  
Rolf Minkwitz ◽  
Arnulf Werner
Keyword(s):  
Low Temperatures ◽  
Spectroscopic Characterization

Abstract The preparation and spectroscopic characterization of the halosulfonium salts CH3(CF3)SHal+ A-(Hal = F, Cl, Br, I, A- = AsF6-, SbF6-, SbCl 6-) is reported. The compounds are synthesized by the reaction of the sulfane CH3SCF3 with XeF+MF6-, Cl2F+AsFf6-, Cl2/AsF5, Cl2/SbCl5 , Br2/AsF5 , or I3+MF6- (M = As, Sb), resp., at low temperatures.

scholarly journals Ab initio spectroscopic characterization of the radical CH3OCH2 at low temperatures

2019 ◽  
Vol 150 (19) ◽  
pp. 194102 ◽  
Author(s):  
O. Yazidi ◽  
M. L. Senent ◽  
V. Gámez ◽  
M. Carvajal ◽  
M. Mogren Al-Mogren
Keyword(s):  
Ab Initio ◽  
Low Temperatures ◽  
Spectroscopic Characterization

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

1984 ◽  
Vol 42 ◽  
pp. 268-269
Author(s):  
E. Knapek ◽  
H. Formanek ◽  
G. Lefranc ◽  
I. Dietrich
Keyword(s):  
Low Temperatures ◽  
Carbon Films ◽  
Organic Crystals ◽  
Wide Spread ◽  
Lens System ◽  
Preparation Conditions ◽  
Thin Carbon ◽  
Electron Diffractograms ◽  
Diffraction Patterns ◽  
Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

Radiation Damage of Support Films

1981 ◽  
Vol 39 ◽  
pp. 28-29
Author(s):  
H.A. Cohen ◽  
W. Chiu
Keyword(s):  
Transfer Function ◽  
Low Temperatures ◽  
Carbon Support ◽  
Contrast Transfer Function ◽  
Electron Dose ◽  
Imaging Parameters ◽  
Negative Stain ◽  
Phase Corrections ◽  
Two Parameters ◽  
Medium Dose

The goal of imaging the finest detail possible in biological specimens leads to contradictory requirements for the choice of an electron dose. The dose should be as low as possible to minimize object damage, yet as high as possible to optimize image statistics. For specimens that are protected by low temperatures or for which the low resolution associated with negative stain is acceptable, the first condition may be partially relaxed, allowing the use of (for example) 6 to 10 e/Å2. However, this medium dose is marginal for obtaining the contrast transfer function (CTF) of the microscope, which is necessary to allow phase corrections to the image. We have explored two parameters that affect the CTF under medium dose conditions.Figure 1 displays the CTF for carbon (C, row 1) and triafol plus carbon (T+C, row 2). For any column, the images to which the CTF correspond were from a carbon covered hole (C) and the adjacent triafol plus carbon support film (T+C), both recorded on the same micrograph; therefore the imaging parameters of defocus, illumination angle, and electron statistics were identical.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

Ultrastructure of the soil fungus, Geomyces pannorus

1984 ◽  
Vol 42 ◽  
pp. 738-739
Author(s):  
J. A. Traquair ◽  
E. G. Kokko
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fine Structure ◽  
Low Temperatures ◽  
Soil Fungus ◽  
Organic Soils ◽  
Anatomical Studies ◽  
Transmission Electron ◽  
Electron Microscopical ◽  
Scanning Electron

With the advent of improved dehydration techniques, scanning electron microscopy has become routine in anatomical studies of fungi. Fine structure of hyphae and spore surfaces has been illustrated for many hyphomycetes, and yet, the ultrastructure of the ubiquitous soil fungus, Geomyces pannorus (Link) Sigler & Carmichael has been neglected. This presentation shows that scanning and transmission electron microscopical data must be correlated in resolving septal structure and conidial release in G. pannorus.Although it is reported to be cellulolytic but not keratinolytic, G. pannorus is found on human skin, animals, birds, mushrooms, dung, roots, and frozen meat in addition to various organic soils. In fact, it readily adapts to growth at low temperatures.

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