Tritium isotope fractionation between hydrogen sulphide and methanol

1983 ◽  
Vol 61 (6) ◽  
pp. 1060-1063 ◽  
Author(s):  
Andrzej Wawer ◽  
Jerzy Szydlowski
Keyword(s):  
Temperature Dependence ◽  
Exchange Reaction ◽  
Isotope Effect ◽  
Hydrogen Sulphide ◽  
Gaseous Phase ◽  
Isotope Fractionation ◽  
Simple Relation ◽  
Temperature Range ◽  
Fractionation Factors ◽  
Good Agreement

Tritium isotope fractionation in the exchange reaction between methanol and hydrogen sulphide has been studied in the gaseous phase over the temperature range 283–373 K. It was found that the heavier isotope accumulates in methanol and that the tritium–protium isotope effect characterizing the exchange reaction studied reaches large values: from 2.70 at 373 K to 3.72 at 283 K. The temperature dependence can be described by the simple relation: In α = −0.1221 + 431.5/T. Using observed vibrational frequencies, theoretical fractionation factors could be calculated and good agreement with the experimentally determined values was observed. The results presently obtained were also compared with those obtained for the CH3SH–H2S system.

Untersuchungen zur Reaktion der Alkoholdehydrogenase mit Tritium-markierten Substraten

1966 ◽  
Vol 21 (6) ◽  
pp. 540-546 ◽  
Author(s):  
Dieter Palm
Keyword(s):  
Alcohol Dehydrogenase ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Substrate Binding ◽  
Isotope Effects ◽  
Direct Interaction ◽  
Enzyme Complex ◽  
Temperature Range ◽  
Yeast Alcohol Dehydrogenase ◽  
Rate Controlling Step

Unexpectedly, the isotope effect of ethanol-1-Τ as a substrate of yeast alcohol dehydrogenase, increases with rising temperature from kH/kT = 3.2 at 5 —15°C to 3.8—4.7 at 20 —35 °C. This suggests a change of the rate controlling step as proposed by MÜLLER-HILL and WALLENFELS, who investigated the temperature dependence of the activation energies in this temperature range. A comparison of the affinities of propanol and butanol with the isotope effects of the corresponding tritium labelled compounds (propanol-1-Τ 6.7 at 25 °C, butanol-1-Τ 6.8 at 25 °C) supports the proposal, that during substrate binding, there must be a direct interaction between the enzyme complex and hydrogen which is removed in the reaction. These influences are less pronounced for the ethanol homologues which are bound less tightly to the enzyme. Therefore the H transfering step proper gives a greater contribution to the overall experimental isotope effect.

Hydrolysis of α-bromoisobutyrate ion in water

1967 ◽  
Vol 45 (18) ◽  
pp. 2071-2077 ◽  
Author(s):  
B. N. Hendy ◽  
W. A. Redmond ◽  
R. E. Robertson
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Deuterium Isotope Effect ◽  
Detailed Mechanism ◽  
Temperature Range ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The temperature dependence of the rate of hydrolysis of α-bromoisobutyrate ion in water was determined over a temperature range 9–37 °C. From these data corresponding values of ΔH≠, ΔS≠, and ΔCP≠ have been derived. The implication of these terms, together with corresponding data for hydrolysis in D2O and for the secondary deuterium isotope effect from the hydrolysis of (CD3)2CBrCOO−, provide a basis for reexamining the detailed mechanism with particular reference to accompanying solvent reorganization.

scholarly journals Temperature dependence of oxygen- and clumped isotope fractionation in carbonates: A study of travertines and tufas in the 6–95°C temperature range

2015 ◽  
Vol 168 ◽  
pp. 172-192 ◽  
Author(s):  
Sándor Kele ◽  
Sebastian F.M. Breitenbach ◽  
Enrico Capezzuoli ◽  
A. Nele Meckler ◽  
Martin Ziegler ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Isotope Fractionation ◽  
Temperature Range ◽  
Clumped Isotope

scholarly journals Band Gap Energy in Silicon

2009 ◽  
Vol 8 (2 and 3) ◽  
Author(s):  
Jeremy Low ◽  
Michael Kreider ◽  
Drew Pulsifer ◽  
Andrew Jones ◽  
Tariq Gilani
Keyword(s):  
Temperature Dependence ◽  
Linear Relationship ◽  
Band Gap ◽  
Energy Gap ◽  
Band Gap Energy ◽  
Constant Current ◽  
Gap Energy ◽  
Temperature Range ◽  
Good Agreement

The band gap energy, Eg in silicon was found by exploiting the linear relationship between the temperature and voltage for the constant current in the temperature range of 275 K to 333 K. Within the precision of our experiment, the results obtained are in good agreement with the known value energy gap in silicon. The temperature dependence of Eg for silicon has also been studied.

scholarly journals Band Gap Energy in Silicon

2008 ◽  
Vol 7 (1) ◽  
Author(s):  
Jeremy Low ◽  
Michael Kreider ◽  
Drew Pulsifer ◽  
Andrew Jones ◽  
Tariq Gilani
Keyword(s):  
Temperature Dependence ◽  
Linear Relationship ◽  
Band Gap ◽  
Energy Gap ◽  
Band Gap Energy ◽  
Constant Current ◽  
Gap Energy ◽  
Temperature Range ◽  
Good Agreement

The band gap energy Eg in silicon was found by exploiting the linear relationship between the temperature and voltage for the constant current in the temperature range of 275 K to 333 K. Within the precision of our experiment, the results obtained are in good agreement with the known value energy gap in silicon. The temperature dependence of Eg for silicon has also been studied.

scholarly journals Gluon condensate and the Polyakov loop

2018 ◽  
Vol 172 ◽  
pp. 02006
Author(s):  
Juan Pablo Carlomagno ◽  
Juan Cristóbal Rojas
Keyword(s):  
Temperature Dependence ◽  
Effective Potential ◽  
Gluon Condensate ◽  
Polyakov Loop ◽  
Temperature Range ◽  
Pure Gauge ◽  
Simple Picture ◽  
Good Agreement

The temperature dependence of the gluon condensate is deduced from the Polyakov loop effective potential. It is shown that this approach provides a simple picture for the electric gluon condensate around the deconfinement temperature, showing that it drops to zero in a temperature range which is in good agreement with different pure gauge lattice results.

scholarly journals Snow isotope diffusion rates measured in a laboratory experiment

2011 ◽  
Vol 57 (201) ◽  
pp. 30-38 ◽  
Author(s):  
L.G. van der Wel ◽  
V. Gkinis ◽  
V.A. Pohjola ◽  
H.A.J. Meijer
Keyword(s):  
Temperature Dependence ◽  
Laboratory Experiments ◽  
Diffusion Length ◽  
Water Isotopes ◽  
Stable Water Isotopes ◽  
Diffusion Rates ◽  
The Difference ◽  
Set Up ◽  
Fractionation Factors ◽  
Good Agreement

AbstractThe diffusion of stable water isotopes in snow was measured in two controlled laboratory experiments. Two batches of snow of different isotopic composition were stacked alternately with varying layer thicknesses. The stack was stored in a freezer room at constant temperature for several months, and sampled at regular intervals to analyse the diffusion. Measured isotope profiles were fitted to a theoretical model with diffusion length as the fit parameter. In the first experiment, we observed a difference in diffusion rates between layers of different thicknesses, which is likely caused by layers of snow not being in proper contact with each other. In the second experiment we found very good agreement between measurements and model results. The measured diffusivity is compared with theory, in which we mainly focus on the temperature dependence of the ice–vapour fractionation factors. This temperature dependence is slightly different for the different isotopes of water, which leads to a difference in diffusion rates. We illustrate how our set-up can be used to measure the ratio between ice–vapour fractionation factors of oxygen-18 and deuterium, which determine the relation between the difference in diffusion and the firn temperature.

The Temperature Dependence of the Diffusion Coefficients of Ar, CO2, CH4, CH3Cl, CH3Br, and CHCl2F in Water

1973 ◽  
Vol 51 (6) ◽  
pp. 944-952 ◽  
Author(s):  
Dow M. Maharajh ◽  
John Walkley
Keyword(s):  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Linear Relationship ◽  
Diffusion Coefficients ◽  
Hard Sphere ◽  
Solute Molecule ◽  
Temperature Range ◽  
Good Agreement

Diffusion coefficient values are reported over a 0 to 35 °C temperature range for Ar, CO2, CH4, CH3Br, CH3Cl, and CHCl2F in water. Various empirical theories relating these diffusion coefficient values to the viscosity of water (η) and the size of the diffusing solute molecule are examined. None are found valid though a linear relationship is found to hold between log D and log η for all systems. McLaughlin's hard sphere theory is examined and found in surprisingly good agreement with experiment. It is seen, however, that this theory cannot adequately predict the temperature dependence of the diffusion coefficient of the solute.

52P1/2 ↔ 52P3/2 excitation transfer in rubidium induced in collisions with CH4, CH2D2, and CD4 molecules

1980 ◽  
Vol 58 (7) ◽  
pp. 1047-1048 ◽  
Author(s):  
R. A. Phaneuf ◽  
L. Krause
Keyword(s):  
Energy Transfer ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Cross Sections ◽  
Noble Gas ◽  
Rotational Energy ◽  
Excitation Transfer ◽  
Sensitized Fluorescence ◽  
Temperature Range ◽  
Rotational Energy Transfer

The temperature dependence of cross sections for 52P1/2 ↔ 52P3/2 excitation transfer in rubidium, induced in collisions with CH4, CH2D2, and CD4 molecules, has been investigated using methods of sensitized fluorescence over a temperature range 300–650 K. The cross sections, which are of the order of 30 Å2 and which exceed similar cross sections for collisions with noble gas atoms by at least two orders of magnitude, exhibit an isotope effect which is ascribed to the phenomenon of electronic-to-rotational energy transfer.

Tracer diffusion of 60Co and 63Ni in amorphous NiZr alloy

1988 ◽  
Vol 3 (1) ◽  
pp. 55-58 ◽  
Author(s):  
K. Hoshino ◽  
R. S. Averback ◽  
H. Hahn ◽  
S. J. Rothman
Keyword(s):  
Amorphous Alloy ◽  
Temperature Dependence ◽  
Ion Beam ◽  
Tracer Diffusion ◽  
Rutherford Backscattering ◽  
Equiatomic Composition ◽  
Serial Sectioning ◽  
Arrhenius Behavior ◽  
Temperature Range ◽  
Good Agreement

Tracer diffusion of 60Co and 63Ni in the amorphous alloy NiZr near the equiatomic composition has been measured in the temperature range between 486 and 641 K using the ion-beam sputter-sectioning technique for serial sectioning. The temperature dependence for the diffusivities of Co and Ni in a-NiZr exhibit Arrhenius behavior; these can be expressed as follows: D∗co = 3.6 × 10−7 exp [− (135 ± 14) kJ mol−1 /RT] m2/s and D∗Ni = 1.7 × 10−7 exp [− (140 ± 9) kJ mol−1 /RT] m2/s. The values of D∗Ni are in good agreement with those measured by the Rutherford backscattering technique. The measured diffusivities were independent of time, indicating that no relaxation took place during diffusion.

Sign in / Sign up

Export Citation Format

Share Document