THE VAPOR-PHASE PHOTOLYSIS OF ACETIC ACID

1955 ◽  
Vol 33 (10) ◽  
pp. 1530-1535 ◽  
Author(s):  
P. Ausloos ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Acetic Acid ◽  
Vapor Phase ◽  
Room Temperature ◽  
Steric Factor ◽  
Primary Process ◽  
Temperature Range ◽  
Abstraction Reaction

The photolysis of acetic acid (CH3COOD) vapor has been investigated in the temperature range from room temperature to 285 °C. Since CH3D formation is independent of temperature, it is certain that the primary process[Formula: see text]occurs to the extent of about 10%. The results are complex and suggest that three other primary processes may occur, viz.[Formula: see text]The abstraction reaction[Formula: see text]is of importance, and the results indicate that it has an activation energy of 10.2 kcal., and a steric factor of the order of 10−3.

THE PHOTO-OXIDATION OF AZOMETHANE

1955 ◽  
Vol 33 (3) ◽  
pp. 496-506 ◽  
Author(s):  
G. R. Hoey ◽  
K. O. Kutschke
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Room Temperature ◽  
Major Product ◽  
Steric Factor ◽  
Primary Process ◽  
Methyl Radicals ◽  
Low Oxygen ◽  
Secondary Product ◽  
Photo Oxidation

The photo-oxidation of azomethane has been studied at low oxygen pressures (0.02 to 1 mm.) in the temperature range ca. 25 °C. to 161 °C. The primary process in the normal photolysis of azomethane is essentially unaffected by the presence of oxygen. Carbon monoxide is probably a secondary product of the oxidation of methyl radicals. Carbon dioxide formation is quite small, and therefore neither methyl radicals nor CH3N=N—CH2 radicals are oxidized appreciably to carbon dioxide. Nitrous oxide, which is a major product of the oxidation, is most likely formed from the oxidation of CH3N=NCH2 radicals. The suggested mechanism of N2O formation is:[Formula: see text] The reaction of methyl radicals with oxygen was found to proceed with a negligible activation energy and a steric factor of the order of 10−2. Evidence for the occurrence of the reactions[Formula: see text]at room temperature was obtained.

About the Electrical Activation of 1×1020 cm-3 Ion Implanted Al in 4H-SiC at Annealing Temperatures in the Range 1500 - 1950°C

2018 ◽  
Vol 924 ◽  
pp. 333-338 ◽  
Author(s):  
Roberta Nipoti ◽  
Alberto Carnera ◽  
Giovanni Alfieri ◽  
Lukas Kranz
Keyword(s):  
Activation Energy ◽  
Sheet Resistance ◽  
Annealing Time ◽  
Thermal Activation ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Thermal Activation Energy ◽  
Electrical Activation ◽  
Temperature Range ◽  
Annealing Temperatures

The electrical activation of 1×1020cm-3implanted Al in 4H-SiC has been studied in the temperature range 1500 - 1950 °C by the analysis of the sheet resistance of the Al implanted layers, as measured at room temperature. The minimum annealing time for reaching stationary electrical at fixed annealing temperature has been found. The samples with stationary electrical activation have been used to estimate the thermal activation energy for the electrical activation of the implanted Al.

Aromatic oxidation by cobaltic acetate in acetic acid

1969 ◽  
Vol 47 (3) ◽  
pp. 387-392 ◽  
Author(s):  
Koichiro Sakota ◽  
Yoshio Kamiya ◽  
Nobuto Ohta
Keyword(s):  
Activation Energy ◽  
Electron Transfer ◽  
Acetic Acid ◽  
Bond Energy ◽  
Hydrogen Abstraction ◽  
Steric Factor ◽  
Benzyl Acetate ◽  
Kcal Mole ◽  
First Order ◽  
Reversible Electron Transfer

A detailed kinetic study of oxidation of toluene and its derivatives by cobaltic acetate in 95 vol% acetic acid is reported. The reaction was found to be profoundly affected by a steric factor and rather insensitive to the C—H bond energy. The order of reactivities of various alkylbenzenes is quite reversal to that of hydrogen abstraction reactions. The reaction was of first-order with respect to toluene, of second-order with respect to cobaltic ion and of inverse first-order with respect to cobaltous ion. The oxidation by cobaltic ion seems to proceed via an initial reversible electron transfer from toluene to cobaltic ion, yielding [Formula: see text] which is oxidized into benzyl acetate by another cobaltic ion. The apparent activation energy for toluene was found to be 25.3 kcal mole−1, and the same activation energy was found for ethylbenzene, cumene, diphenylmethane, and triphenylmethane.

ADDITION OF ETHYL RADICALS TO ETHYLENE

1957 ◽  
Vol 35 (7) ◽  
pp. 588-594 ◽  
Author(s):  
J. A. Pinder ◽  
D. J. Le Roy
Keyword(s):  
Activation Energy ◽  
Reaction Zone ◽  
Addition Reaction ◽  
Steric Factor ◽  
Square Root ◽  
Temperature Range ◽  
Ethyl Radical ◽  
Ethyl Radicals

The addition of ethyl radicals to ethylene has been studied in the temperature range 58° to 123 °C. The radicals were produced by the mercury photosensitized decomposition of hydrogen in the presence of ethylene, and the rate of the addition reaction was measured in terms of the rate of formation of n-hexane by the combination of ethyl and butyl radicals. Corrections were made for the non-uniformity of radical concentrations in the reaction zone. Assuming a negligible activation energy for the combination of two ethyl radicals, the activation energy for the addition reaction is 5.5 kcal. per mole; the steric factor, relative to the square root of the steric factor for ethyl radical combination, is 5.0 × 10−5.

THE PHOTOLYSIS OF AZOISOPROPANE

1953 ◽  
Vol 31 (4) ◽  
pp. 377-384 ◽  
Author(s):  
R. W. Durham ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Excited Molecule ◽  
Energy Difference ◽  
Effect Of Pressure ◽  
Temperature Range ◽  
Excited Molecules

Azoisopropane has been photolyzed by 3600 Å radiation over the temperature range 30–120 °C. The effect of pressure indicates an excited molecule mechanism. Excited molecules which decompose give nitrogen and isopropyl radicals; the latter either combine, disproportionate, or react with azoisopropane. The activation energy difference between the two reactions[Formula: see text]has been found to be 6.5 ± 0.5 kcal. per mole.The difference in activation energy between the disproportionation and combination reactions is rendered ambiguous by the possibility of C3H7.N:N existing at the lower temperatures; but this is certainly small. The ratio of the rates of the two reactions is 0.5 at room temperature.

THE MERCURY PHOTOSENSITIZED HYDROGENATION OF PROPYLENE AND THE ACTIVATION ENERGY OF THE REACTION C3H7+H2 = C3H8+H

1955 ◽  
Vol 33 (4) ◽  
pp. 580-588 ◽  
Author(s):  
G. R. Hoey ◽  
D. J. Le Roy
Keyword(s):  
Activation Energy ◽  
Hydrogen Pressure ◽  
Room Temperature ◽  
Linear Functions ◽  
Analogous Reaction ◽  
Temperature Range ◽  
Pressure Decrease

The reactions initiated in hydrogen–propylene mixtures by Hg(3P1) atoms were studied over the temperature range from room temperature to 320 °C. At 260° and above, the rate of formation of propane and the rate of pressure decrease are linear functions of the hydrogen pressure. This effect is attributed to the reaction C3H7+H2 = C3H8+H and its activation energy is estimated to be equal to or slightly greater than 12.5 kcal. per mole. This is 1.2 kcal. per mole greater than the corrected value for the activation energy of the analogous reaction C2H5+H2 = C2H6+H. The ratio kcombination/kdispropotionation is estimated to be approximately 2.0 at room temperature in the case of isopropyl radicals.

APPLICATION OF DIFFUSION FLAME TECHNIQUE TO THE REACTION BETWEEN NITROGEN ATOMS AND ETHYLENE

1949 ◽  
Vol 27b (8) ◽  
pp. 732-737
Author(s):  
C. A. Winkler ◽  
J. H. Greenblatt
Keyword(s):  
Activation Energy ◽  
Temperature Coefficient ◽  
Diffusion Flame ◽  
Rate Constants ◽  
Steric Factor ◽  
Temperature Range

Rate constants for the reaction between nitrogen atoms and ethylene have been obtained by diffusion flame technique over the temperature range 273° to 373 °C. An activation energy of about 3 kcal. has been obtained from the temperature coefficient of these rate constants, and using this value a steric factor of 10−2 has been calculated.

THE REACTION OF METHYL RADICALS WITH FORMALDEHYDE

1959 ◽  
Vol 37 (4) ◽  
pp. 672-678 ◽  
Author(s):  
S. Toby ◽  
K. O. Kutschke
Keyword(s):  
Activation Energy ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Formyl Radical ◽  
Temperature Range ◽  
Abstraction Reaction

Azomethane was photolyzed in the presence of up to 30 mole per cent formaldehyde and formaldehyde-d2 at temperatures from 80 °C to 180 °C. The value of the activation energy for the abstraction reaction with methyl radicals was found to be 6.2 kcal mole−1 for CH2O and 7.9 kcal mole−1 for CD2O. The results indicated that the formyl radical was stable over the temperature range studied.

REACTION OF OXYGEN ATOMS WITH ACETALDEHYDE

1956 ◽  
Vol 34 (6) ◽  
pp. 775-784 ◽  
Author(s):  
R. J. Cvetanović
Keyword(s):  
Activation Energy ◽  
Nitrous Oxide ◽  
Room Temperature ◽  
Primary Process ◽  
Kcal Mole ◽  
Decomposition Of Nitrous Oxide ◽  
Oxygen Atoms

Reaction of oxygen atoms, produced by mercury photosensitized decomposition of nitrous oxide, with acetaldehyde has been studied at room temperature. The major products of the reaction are water and biacetyl and the only primary process appears to be[Formula: see text]followed by[Formula: see text]and[Formula: see text]At room temperature oxygen atoms react with acetaldehyde 0.7 ± 0.1 times as fast as with ethylene, so that the activation energy of reaction [1] is likely to be close to 3 kcal./mole.

Kinetics of Cu Segregation in Al-Cu(1at% Cu) Interconnects Studied by Resistance Measurements

1997 ◽  
Vol 473 ◽  
Author(s):  
A. J. Kalkman ◽  
A. H. Verbruggen ◽  
G. C. A. M. Janssen ◽  
S. Radelaar
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Grain Boundary ◽  
Room Temperature ◽  
Boundary Diffusion ◽  
Measurement Temperature ◽  
Temperature Range ◽  
Different Temperatures ◽  
Resistance Decrease ◽  
Kinetics Of

ABSTRACTThe time-dependence of the growth of Al2Cu precipitates in Al-Cu(lat% Cu) thin films is studied by means of resistance measurements at different temperatures. The samples are annealed at 400°C for 1 hour, and then quickly cooled down to room temperature. Afterwards, the samples are heated within one minute to a measurement temperature between 140 °C and 240 °C. Growth of precipitates causes a well defined decrease in resistance. The observed resistance decrease does not follow an exponential decay. In the investigated temperature range the resistance decrease can be accurately modelled by (R(t)-R∞) = (Ro-R∞)exp(-(t /τ)n), with the time constant τ= τ0 exp(Ea / kT). Excellent fits were obtained resulting in n = 0.66±0.05, independent of temperature, and Ea= 0.81±0.03 eV. This value for the activation energy agrees very well with the activation energy that has been reported in literature for both electromigration failure in Al-Cu and grain-boundary diffusion of Cu in Al. The value we found for n is intriguingly close to 2/3 and deviates strongly from the values of n reported for bulk Al-Cu (n = 1.5–1.8) in the same temperature range.

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