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.

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.

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.

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.

Luminescence Properties of Eu ion-implanted GaN

2003 ◽  
Vol 798 ◽  
Author(s):  
Shin-ichiro Uekusa ◽  
Isao Tanaka
Keyword(s):  
Activation Energy ◽  
Electron Emission ◽  
Radiative Recombination ◽  
Room Temperature ◽  
Thermal Quenching ◽  
Temperature Dependent ◽  
Room Temperature Photoluminescence ◽  
Temperature Range ◽  
Quenching Process ◽  
The Eu

ABSTRACTThe Eu ion was implanted at an energy of 300keV with a dose of 1×1015cm-2 at room temperature. Photoluminescence (PL) and PL lifetime were characterized and studied on thermal quenching process. We calculated the activation energy (E1) of temperature dependent PL and the value of E1 was 5.68meV. E1 was affected the luminescence intensity in the temperature range from 15K to 70K. The activation energy (Ea) of PL lifetime was calculated and the value of Ea was 8.5meV. The non-radiative recombination in the transition from the 5D0 to 7F2 of Eu was dominated in the temperature range from 15K to 100K. We found that the thermal quenching occurred in both the electron emission from RE-trap and the non-radiative recombination in the transition on Eu in the temperature range from 15K to 70K.

THE PYROLYSIS OF DIALLYL (1,5-HEXADIENE)

1960 ◽  
Vol 38 (6) ◽  
pp. 827-834 ◽  
Author(s):  
D. J. Ruzicka ◽  
W. A. Bryce
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Radical Mechanism ◽  
Static System ◽  
Kcal Mole ◽  
Temperature Range ◽  
Gaseous Products ◽  
Mechanism Of Decomposition ◽  
Liquid Products

The mechanism of decomposition of diallyl has been studied in a static system in the temperature range 460–520 °C. The principal gaseous products (room temperature) were propylene, methane, ethylene, and 1-butene, and the liquid products were cyclopentene, cyclopentadiene, 1-hexene, and benzene. The over-all activation energy of decomposition was 31.3 ± 1.0 kcal/mole for an A factor of 107 sec−1. A mechanism of decomposition based on hydrogen abstraction by allyl and the addition of allyl to olefinic double bonds is proposed. Some decomposition by a non-radical mechanism may also occur.

The kinetics of the reaction between O 2 ( 1 ∆ g ) and ozone

1970 ◽  
Vol 317 (1530) ◽  
pp. 407-416 ◽  
Keyword(s):  
Activation Energy ◽  
Rate Constant ◽  
Room Temperature ◽  
Published Data ◽  
Temperature Range ◽  
A Value ◽  
Kinetics Of

The kinetics of the reaction O 2 ( 1 ∆ g ) + O 3 k 2 → 2O 2 + O have been investigated in the temperature range 195 to 439 K by using the kinetic photo­ionization technique to follow [O 2 ( 1 ∆ g )]. In Arrhenius form, the rate constant, k 2 ,'is given by k 2 = 4.0 ± 1.5 x 10 8 exp (13000 /RT) 1 mol -1 s -1 (joule units) ( = 4.0 ± 1.5 x 10 8 exp (3100/RT) 1 mol -1 s -1 (calorie units)). At room temperature (292 K) k 2 = 2.1 ± 0.3 x 10 6 1 mol -1 s -1 . The activation energy of 13 ± 1.6 kJ mol -1 suggests that there is virtually no barrier to the reaction other than that provided by its endothermicity (12.1 kJ mol -1 ). The results are used to derive, from pre­viously published data, a value of the rate constant for the reaction O + O 3 k 3 → 2O 2 of 4 ± 2 x 10 6 1 mol -1 s -1 at room temperature.

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.

Mössbauer study of the reduction of α-Fe2O3 in hydrogen

1980 ◽  
Vol 58 (14) ◽  
pp. 1473-1475 ◽  
Author(s):  
Dimitar G. Klissurski ◽  
Ivan G. Mitov ◽  
Trifon Tomov
Keyword(s):  
Activation Energy ◽  
Hydrogen Pressure ◽  
Mössbauer Spectra ◽  
Reaction Order ◽  
Kinetics And Mechanism ◽  
Mössbauer Study ◽  
Circulation Method ◽  
Temperature Range ◽  
Mossbauer Spectra

The kinetics and mechanism of reduction of α-Fe2O3 by hydrogen has been studied by a static circulation method in the temperature range 220–350 °C. It has been established that the reaction order with respect to the hydrogen pressure is 0.86 ± 0.07 and the activation energy of the process is 17.9 ± 0.7 kcal/mol. The kinetic results and the Mössbauer spectra of specimens reduced to different degrees have shown no accumulation of wüstite phase during the reaction.

On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

2021 ◽  
pp. 009524432110203
Author(s):  
Sudhir Bafna
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Dwell Time ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Kinetics Of ◽  
Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

Sign in / Sign up

Export Citation Format

Share Document