Proton Rotating Frame Relaxation in Lithium Hydrazinium Sulfate, Li(N2H5)SO4

1971 ◽  
Vol 49 (7) ◽  
pp. 870-875 ◽  
Author(s):  
R. R. Knispel ◽  
H. E. Petch
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Temperature Dependence ◽  
Rotating Frame ◽  
Kcal Mole ◽  
Second Moment ◽  
Rotating Frame Relaxation ◽  
And Diffusion

The temperature dependence of the rotating frame relaxation time T1ρ for protons in powdered lithium hydrazinium sulfate, Li(N2H5)SO4, has been determined from 140 to 495 °K. These measurements indicate that the –NH2 part of the N2H5+ ion executes 180° flips about the bisectrix of the H–N–H angle with activation energy of 10.7 ± 0.5 kcal/mole. Evidence for motion of the entire N2H5+ ion with activation energy of 17.4 ± 1.1 kcal/mole was also obtained. Separate reorientation and diffusion motions of the N2H5+ ion could not be distinguished, although evidence that the N2H5+ motion detected in the T1ρ measurements includes diffusion is obtained by comparing the T1ρ results with the temperature dependence of the proton second moment.

scholarly journals Balanced spin‐lock preparation for B 1 ‐insensitive and B 0 ‐insensitive quantification of the rotating frame relaxation time T 1ρ

2020 ◽  
Author(s):  
Maximilian Gram ◽  
Michael Seethaler ◽  
Daniel Gensler ◽  
Johannes Oberberger ◽  
Peter M. Jakob ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Rotating Frame ◽  
Spin Lock ◽  
Rotating Frame Relaxation

scholarly journals The activation energy of viscoelastic deformation of rocks

2003 ◽  
pp. 101-105
Author(s):  
Dzhema Melkonyan
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Temperature Dependence ◽  
Probabilistic Approach ◽  
Deformation Energy ◽  
Total Probability ◽  
Suggested Model ◽  
Viscoelastic Deformation ◽  
Viscous Deformation

The suggested model, which considers the simultaneous appearance (on the intermolecular scale) of elastic and viscous behaviors of rocks during their viscoelastic deformation, enables the relaxation time, t0, of the viscoelastic deformation energy to be defined. By determination of t0, the activation energies of the elastic and viscous deformation can be separated from the temperature dependence of the viscoelastic deformation energy stream U. The probabilistic approach to viscoelastic deformation of rocks allows the introduction of the a notion of the total probability, consisting of the probabilities of elastic and viscous deformations.

Longitudinal rotating frame relaxation time measurements in infarcted mouse myocardium in vivo

2012 ◽  
Vol 69 (5) ◽  
pp. 1389-1395 ◽  
Author(s):  
Haja-Sherief N. Musthafa ◽  
Galina Dragneva ◽  
Line Lottonen ◽  
Mari Merentie ◽  
Lyubomir Petrov ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Rotating Frame ◽  
Rotating Frame Relaxation

Rotating-frame relaxation time study of hydrogen diffusion in ZrHx

1984 ◽  
Vol 17 (19) ◽  
pp. L477-L482 ◽  
Author(s):  
R C Bowman ◽  
B D Craft
Keyword(s):  
Relaxation Time ◽  
Hydrogen Diffusion ◽  
Rotating Frame ◽  
Time Study ◽  
Rotating Frame Relaxation

Vulcanization of Elastomers. 21. Vulcanization of Natural Rubber with Thiuram Disulfides. VI

1959 ◽  
Vol 32 (2) ◽  
pp. 566-576
Author(s):  
Walter Scheele ◽  
Klaus Hummel
Keyword(s):  
Activation Energy ◽  
Natural Rubber ◽  
Temperature Dependence ◽  
Sulfur Content ◽  
Rate Constants ◽  
Order Reaction ◽  
First Order Reaction ◽  
Kcal Mole ◽  
First Order ◽  
Limiting Value

Abstract Bound sulfur in a pure thiuram vulcanizate increases relatively rapidly at first at all temperatures, reaches a poorly defined maximum at about 27 to 30%, independent of temperature, and then recedes slightly to reach a limiting value of 25% also independent of temperature, based on the original thiuram disulfide. The rise in sulfur content at the start points to a temperature-independent limiting value of 33%. It is shown that the combination of sulfur in this region initially follows a first order reaction, and goes at the same rate as the reduction in concentration of thiuram disulfide. It can be seen from the above that sulfur may be combined in thiuram vulcanization without simultaneous crosslinking. The dithiocarbamate formation increases rapidly in the region of longer vulcanization times, after the maximum in bound sulfur has been reached, without further combination of sulfur with the vulcanizate. The rate constants for thiuram decrease, for dithiocarbamate increase and for sulfur combination were calculated. The temperature dependence of each of these reactions has practically the same activation energy, 23 kcal/mole. The bound sulfur content of the vulcanizates in pure thiuram vulcanizations is no criterion of the state of vulcanization.

Proton dynamics in ferroelectric colemanite

1970 ◽  
Vol 48 (9) ◽  
pp. 1081-1085 ◽  
Author(s):  
A. Watton ◽  
H. E. Petch ◽  
M. M. Pintar
Keyword(s):  
Temperature Dependence ◽  
Line Width ◽  
Hydroxyl Group ◽  
Water Molecules ◽  
Kcal Mole ◽  
Hydrogen Atoms ◽  
Second Moment ◽  
Diffraction Model ◽  
Proton Dynamics ◽  
Good Agreement

A reexamination of the proton second moment in powdered colemanite, CaB3O4(OH)3∙H2O, over the range 4.2–450 °K has shown that the temperature dependence is in qualitative agreement with earlier work but that the magnitudes of the changes occurring at the two line-width transitions are substantially different. The observed values of the second moment have been compared with values calculated on the basis of models in which the hydrogen-containing molecular groups reorient. The line-width transition at about 130 °K is attributed to a motion in which the water molecules undergo 180° flips about the bisectrix of the H—O—H angle. The activation energy for this motion has been determined as 5.3 ± 0.3 kcal/mole from the temperature dependence of T1. The observed change in the second moment at the ferroelectric transition (270 °K) is in good agreement with the value calculated on the basis of the neutron diffraction model, in which a cooperative motion involving one of the hydrogen atoms of the water molecule and the hydrogen of an adjacent hydroxyl group is active above the transition.

Localization of Conduction Band Electrons in Polycrystalline Ti02 Studied by ESR

1981 ◽  
Vol 36 (3) ◽  
pp. 226-232 ◽  
Author(s):  
E. Serwicka ◽  
M. W. Schlierkamp ◽  
R. N. Schindler
Keyword(s):  
Activation Energy ◽  
Electron Transfer ◽  
Temperature Dependence ◽  
Conduction Band ◽  
Electron Acceptor ◽  
Electron Mobility ◽  
Signal Intensity ◽  
Esr Spectra ◽  
Electron Acceptors ◽  
Kcal Mole

Adsorption of electron acceptors on partially reduced TiO2 leads to the localization of mobile conduction band electrons which is indicated by the appearance of an ESR signal with g = 2.003. The localization process is accompanied by an electron transfer from donor centers in reduced TiO2 (Ti3+ ions) to adsorbed molecules. The ESR spectra show a decrease of the Ti3+ signal intensity at gr -1.96. Additionally, in the case of O2, SO2 and C6H5NO2 adsorption, the ESR signals of the respective anion radicals are observed. Illumination of samples with an electron acceptor adsorbed enhances the g - 2.003 signal. The activation energy corresponding to the temperature dependence of the localization process has been determined to be ~ 1 kcal/mole in the temperature range - 140 to - 40 °C. In the case of O2 and N2O the signal at g = 2.003 could be annihilated chemically by using propylene which reacted with the adsorbed electron acceptor and thus removed the species which reduced the electron mobility

Dielectric Behaviour in the MHz range of cis-bis (glycynato)Cu(II) monohydrate and (glycylglycinato)Cu(II) trihydrate in Water

1976 ◽  
Vol 31 (9) ◽  
pp. 1085-1088 ◽  
Author(s):  
P. U. Sakellaridis ◽  
E. K. Karageorgopoulos
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Dipole Moment ◽  
Relaxation Time ◽  
Dielectric Properties ◽  
Charge Separation ◽  
Rotational Relaxation ◽  
Kcal Mole ◽  
Dielectric Absorption ◽  
Molecular Radius

Abstract The dielectric properties of Cu(gly)2 and Cu(glygly) in diluted aqueous solution were examined in the MHz range at 273 to 313 K. The complexes exhibit dielectric absorption in the ranges 5.09X107 to 9.34X107 Hz and 4.63X107 to 8.01X107 Hz, respectively, depending on concentration and temperature. This absorption was attributed to rotational relaxation of the unhydrated and monohydrated complexes. The following data for the two complexes in solution at 293 K have been obtained, respectively: dipole moment 19.3 D and 34.0 D, charge separation 2.01 A and 3.54 Å, relaxation time 2.3X10-9 sec and 2.6X10-9 sec, molecular radius 6.36 Å and 6.47 Å, activation energy for the relaxation process 5.6 kcal mole-1 for both complexes.

Uniaxial Reorientation of Octahedral Complex Anions Excited in Triethylammonium Hexachlorostannate (IV) Crystals

1992 ◽  
Vol 47 (1-2) ◽  
pp. 283-287 ◽  
Author(s):  
Takashige Shimizu ◽  
Tetsuo Asaji ◽  
Daiyu Nakamura ◽  
Ryuichi Ikeda
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Complex Anion ◽  
The Other ◽  
Octahedral Complex ◽  
Complex Ions ◽  
Complex Anions

AbstractThe temperature dependence of the 35Cl NQR spin-latticew relaxation time T1Q has been determined for the three resonance lines observed in [ ( C2H5 ) 3NH]2SnCl6 . The higher frequency lines fade out around 150 K upon heating, whereas the lowest line shows up to room temperature no anomaly, although these three lines are assigned to chlorines belonging to the same complex anion. The T1Q values of the higher two lines decrease exponentially around the fade-out temperature, where T1q of the lowest line shows no such behavior. These results are explained by the onset of uniaxial reorientations of the octahedral complex ions by 90° about the Cl -Sn -Cl axis containing the lowest frequency chlorines. The activation energy ( Ea)of this reorientation (22-24 kJ mol-1 ) is the lowest so far reportd for [SnCl6 ] 2 - ions. Ea about the other axes is 67 kJ mol-1 , indicating a remarkable anisotropic reorientation.

Spin–lattice relaxation in liquid ethylene chloride

1970 ◽  
Vol 48 (17) ◽  
pp. 2785-2786
Author(s):  
E. Bock ◽  
G. Wollner ◽  
E. Tomchuk
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Total Spin ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Kcal Mole ◽  
Spin Lattice ◽  
Ethylene Chloride

The proton spin – lattice relaxation time of ethylene chloride in deuterated ethylene chloride was determined as a function of concentration and temperature over the temperature range 230 to 390 °K. It was found that the activation energy for the total spin–lattice relaxation as well as for the intra-molecular contribution to the total spin–lattice relaxation was 2.0 kcal/mole and was nearly equal to the activation energy for viscous flow, viz. 2.3 kcal/mole.

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