Notizen:Kernmagnetische Relaxationszeit-Messungen an OH-Protonen einer kristallinen Kieselsäure/ Nuclear Magnetic Relaxation Measurements on the OH-Protons of a Crystalline Silicic Acid

1975 ◽  
Vol 30 (10) ◽  
pp. 1330-1332 ◽  
Author(s):  
E. K.-H. Wittich ◽  
J. Voitländer ◽  
G. Lagaly
Keyword(s):  
Thermal Decomposition ◽  
Silicic Acid ◽  
Magnetic Relaxation ◽  
Interlayer Space ◽  
Relaxation Times ◽  
Water Molecules ◽  
Relaxation Processes ◽  
Relaxation Measurements ◽  
Silicate Layers ◽  
Crystalline Silicic Acid

Abstract The transversal relaxation times of the OH-protons of a crystalline silicic acid were measured. Two relaxation processes, clearly separated from each other, are related to the OH-protons in the silicate layers and to the OH-protons of water molecules in the interlayer spaces. From the initial magnetizations information is obtained about the water content in the interlayer space which does well agree with results given in thermal decomposition curves.

Messung kernmagnetischer Relaxationszeiten in Hochauflösung mittels schneller adiabatischer Passagen

1970 ◽  
Vol 25 (11) ◽  
pp. 1674-1680
Author(s):  
Hans Lütje
Keyword(s):  
High Resolution ◽  
Polyethylene Oxide ◽  
Magnetic Relaxation ◽  
Chemical Shifts ◽  
Signal To Noise Ratio ◽  
Relaxation Times ◽  
Resonance Signal ◽  
Additional Equipment ◽  
Relaxation Measurements ◽  
Fast Passage

Abstract The nuclear magnetic relaxation times T1 and T2 may be determined by observing the relaxation that follows after a stop of an adiabatic fast passage at different points of the resonance signal. High resolution measurements are possible with external proton stabilization during the relaxation process if the chemical shifts are larger than 1 ppm and the relaxation times are longer than 1 sec. If no high resolution is required the lower limit is 0.2 seconds. Relaxation measurements are possible using conventional NMR-spectrometers without additional equipment. Since the signal to noise ratio is favourable, rather dilute solutions may be investigated. Relaxation measurements on benzene, on 4 different protons of 4-dimethylamino-benzaldehyde and on polyethylene oxide in solution are reported.

Energy transfer in polyatomic molecules. II. Relative catalytic efficiency for energy transfer to different vibrations to the same molecule

1961 ◽  
Vol 264 (1318) ◽  
pp. 299-308 ◽  
Keyword(s):  
Energy Transfer ◽  
Sulphur Dioxide ◽  
Deuterium Oxide ◽  
Relaxation Times ◽  
Catalytic Efficiency ◽  
Polyatomic Molecules ◽  
Fair Agreement ◽  
Water Molecules ◽  
Relaxation Processes ◽  
Ultrasonic Measurements

Vibrations of sulphur dioxide show two separate relaxation times. Values of r 1 = 6.0 × 10 -8 s for the vibrations of 519 cm -1 and r 2 = 1.2 × 10 -6 s for the vibrations of 1151 and 1361 cm -1 have been derived from new ultrasonic measurements, in fair agreement with earlier work. Molecules studied as possible vibration-translation catalysts included ethane, ethylene, water, and n -hexane. No enhanced efficiency of energy transfer was observed with ethylene. Ethane and water molecules were found to be only moderately efficient catalysts; proportionally, they exert a greater effect for processes associated with r 1 . Deuterium oxide is found to be somewhat more efficient than water. n -Hexane is highly efficient for both the r 1 and r 2 relaxation processes of sulphur dioxide. These observations are discussed in relation to various mechanisms for the catalysis of energy transfer.

scholarly journals Activating cement mixing water with the relaxation processes

2020 ◽  
Vol 8 (4) ◽  
pp. 43-48
Author(s):  
Andrei Pavlov ◽  
Yurii Gol'tsov ◽  
Levon Mailyan ◽  
Evgeniy Shcherban' ◽  
Sergey Stel'makh ◽  
...  
Keyword(s):  
Relaxation Times ◽  
Free Water ◽  
Water Molecules ◽  
Relaxation Processes ◽  
Activity Time ◽  
Thermodynamically Equilibrium ◽  
Melt Water ◽  
Radiation Activation ◽  
The Common ◽  
Mixing Water

The analysis of relaxation processes in water activated by thermal or ultraviolet radiation has been carried out. The activation of the mixing water leads to an earlier hardening of the cement. At the same time, activated water loses its properties with a relaxation time, which is equal to the activity time of melt water, which is explained by the common reasons for the origin of the increased reaction properties of activated water and melt water. These properties are due to the fact that activation increases the content of free water molecules. In the normal state, some of the water molecules enter the voids of fractal-clathrate structures. During thermal or radiation activation processes, characterized by certain relaxation times, these structures are destroyed, and free water molecules are released. But after the termination of activation, relaxation processes take place to restore thermodynamically equilibrium fractal-clathrate structures, and part of the free water is again captured by these structures. Therefore, the reactivity of water after the termination of activation decreases.

scholarly journals Über die Natur der Siliciumdioxidmodifikation Silica-X / On the Nature of the Silica Modification "silica-X"

1979 ◽  
Vol 34 (4) ◽  
pp. 648-649 ◽  
Author(s):  
Klaus Beneke ◽  
Gerhard Lagaly
Keyword(s):  
Cation Exchange ◽  
Silicic Acid ◽  
Potassium Silicate ◽  
Silica Modification ◽  
Crystalline Silicic Acid

Abstract Silica-X described in 1964 as a new SiO2 modification is the dehydrated form of the crystalline silicic acid H2Si8O17 · xH2O which is obtained by cation exchange from the potassium silicate K2Si8O17 · xH2O.

Restricted Rotational Motion of InterlayerWaterMolecules in Vanadium Pentoxide Hydrate, V2O5·n D2O, as Studied by Deuterium NMR

2002 ◽  
Vol 57 (6-7) ◽  
pp. 419-424 ◽  
Author(s):  
Sadamu Takeda ◽  
Yuko Gotoh ◽  
Goro Maruta ◽  
Shuichi Takahara ◽  
Shigeharu Kittaka
Keyword(s):  
Double Layer ◽  
Vanadium Pentoxide ◽  
Rotational Motion ◽  
Interlayer Space ◽  
Layer Structure ◽  
Bond Distance ◽  
Adsorbed Water ◽  
Deuterium Nmr ◽  
Water Molecules ◽  
Layer Structures

The rotational behavior of the interlayer water molecules of deuterated vanadium pentoxide hydrate, V2O5.nD2O, was studied by solid-state deuterium NMR for the mono- and double-layer structures of the adsorbed water molecules. The rotational motion was anisotropic even at 355 K for both the mono- and double-layer structures. The 180° flipping motion about the C2-symmetry axis of the water molecule and the rotation around the figure axis, which makes an angle Ɵ with the C2-axis, occurred with the activation energy of (34±4) and (49±6) kJmol-1, respectively. The activation energies were almost independent of the mono- and double-layer structures of the water molecules, but the angle Ɵ made by the two axes varied from 33° for the monolayer to 25° for the double-layer at 230 K. The angle started to decrease above 250 K (e. g. the angle was 17 at 355 K for the double-layer structure). The results indicate that the average orientation of the water molecules in the two dimensional interlayer space depends on the layer structure and on the temperature. From the deuterium NMR spectrum at 130 K, the quadrupole coupling constant e2Qq/h = 240 kHz and the asymmetry parameter η= 0.12 were deduced. These values indicate the average hydrogen bond distance R(O H) = 2.0 Å for the D2O molecules in the 2D-interlayer space

Relaxation processes of some simple aliphatic molecules in dilute solutions

1977 ◽  
Vol 55 (4) ◽  
pp. 297-301 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Carbon Tetrachloride ◽  
Dielectric Relaxation ◽  
Thermodynamic Parameters ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Dilute Solutions ◽  
Microwave Region ◽  
Nonpolar Solvents ◽  
Dielectric Data ◽  
Intramolecular Rotation

The dielectric relaxation processes of acetone, cyclohexanone, 4-methyl-2-pentanone, and 4-heptanone in dilute nonpolar solvents, n-heptane, cyclohexane, benzene, and carbon tetrachloride have been studied in the microwave region over a temperature range 10 to 60 °C. The relaxation times and the thermodynamic parameters for the activated states have been determined using the measured dielectric data. The results have been discussed in terms of dipole reorientation by molecular and intramolecular rotation and compared, wherever possible, with other similar studies on aliphatic molecules.

Relaxation processes of quinoline, isoquinoline, and their mixtures

1980 ◽  
Vol 58 (1) ◽  
pp. 20-24 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Thermodynamic Parameters ◽  
Molecular Motion ◽  
Polar Solvent ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Polar Components ◽  
Dielectric Absorption ◽  
System A ◽  
Dielectric Data ◽  
Activated State

The dielectric absorption of quinoline, isoquinoline, and their binary mixtures has been studied in the microwave region over a range of temperatures in dilute benzene and n-heptane solutions. The relaxation times and the thermodynamic parameters for the activated state have been determined using the measured dielectric data. The results obtained have been discussed in terms of the molecular motion of the system. A relation has been proposed to represent the relaxation behavior of a system of two Debye-type polar components in a non-polar solvent. The relation has been tested by comparing the calculated values with those determined experimentally for a few systems consisting of similar, simple rigid polar molecules.

Temperature Dependence of Dynamic Properties of Elastomers. Relaxation Distributions

1952 ◽  
Vol 25 (4) ◽  
pp. 720-729 ◽  
Author(s):  
John D. Ferry ◽  
Edwin R. Fitzgerald ◽  
Lester D. Grandine ◽  
Malcolm L. Williams
Keyword(s):  
Distribution Function ◽  
Temperature Dependence ◽  
Dynamic Properties ◽  
Relaxation Times ◽  
Dynamic Mechanical Properties ◽  
Relaxation Processes ◽  
The Real ◽  
Reduced Frequency ◽  
Dynamic Rigidity ◽  
Composite Curve

Abstract By the use of reduced variables, the temperature dependence and frequency dependence of dynamic mechanical properties of rubberlike materials can be interrelated without any arbitrary assumptions about the functional form of either The definitions of the reduced variables are based on some simple assumptions regarding the nature of relaxation processes. The real part of the reduced dynamic rigidity, plotted against the reduced frequency, gives a single composite curve for data over wide ranges of frequency and temperature; this is true also for the imaginary part of the rigidity or the dynamic viscosity. The real and imaginary parts of the rigidity, although independent measurements, are interrelated through the distribution function of relaxation times, and this relation provides a check on experimental results. First and second approximation methods of calculating the distribution function from dynamic data are given. The use of the distribution function to predict various types of time-dependent mechanical behavior is illustrated.

Cu(ii)–Dy(iii) and Co(iii)–Dy(iii) based single molecule magnets with multiple slow magnetic relaxation processes in the Cu(ii)–Dy(iii) complex

2015 ◽  
Vol 44 (29) ◽  
pp. 13242-13249 ◽  
Author(s):  
Malay Dolai ◽  
Mahammad Ali ◽  
Ján Titiš ◽  
Roman Boča
Keyword(s):  
Schiff Base ◽  
Single Molecule ◽  
Schiff Base Ligand ◽  
Magnetic Relaxation ◽  
Magnetic Behaviour ◽  
Dinuclear Complexes ◽  
Relaxation Processes ◽  
Single Molecule Magnets ◽  
Slow Magnetic Relaxation

Two CuII–DyIII and CoIII–DyIII dinuclear complexes of a Schiff base ligand (H3L) exhibit single-molecule magnetic behaviour with multiple slow magnetic relaxation processes for the former.

Relaxation Time Spectrum, Elasticity, and Viscosity of Rubber. I

1954 ◽  
Vol 27 (1) ◽  
pp. 36-54 ◽  
Author(s):  
W. Kuhn ◽  
O. Künzle ◽  
A. Preissmann
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Time Spectrum ◽  
Test Sample ◽  
Elastic Behavior ◽  
Relaxation Processes ◽  
Relaxation Time Spectrum ◽  
Restoring Force ◽  
Constant Length ◽  
Rapid Deformation

Abstract By rapid deformation of a medium in which linear molecules are present, various changes are produced simultaneously in the latter. These changes are more or less independent of one another, and can release independently and totally or partially by rearrangement of valence distances and valence angles in the chain molecules. By virtue of such relaxation processes, a portion of the stress originating in the rapid deformation disappears, with a changing time requirement for the various portions. A relaxation time spectrum is thus formed. The relaxation time spectrum consists of a finite number of restoring force mechanisms with proper relaxation times or of a continuous spectrum. Both the creep curves (the dependence of the length of a body on time at constant load), and stress relaxation (decay of the stress observed in test sample kept at constant length after rapid deformation), as well as the total visco-elastic behavior, especially the behavior at constant periodic deformation of the test sample, are determined by the relaxation time spectrum. The appropriate Quantitative relationships were derived.

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