Determination of anisotropy of molecular motion with carbon-13 spin-lattice relaxation times

1975 ◽  
Vol 97 (7) ◽  
pp. 1805-1808 ◽  
Author(s):  
Stefan Berger ◽  
Fritz R. Kreissl ◽  
David M. Grant ◽  
John D. Roberts
Keyword(s):  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice

ChemInform Abstract: DETERMINATION OF ANISOTROPY OF MOLECULAR MOTION WITH (13)C SPIN-LATTICE RELAXATION TIMES

1975 ◽  
Vol 6 (24) ◽  
Author(s):  
STEFAN BERGER ◽  
FRITZ R. KREISSL ◽  
DAVID M. GRANT ◽  
JOHN D. ROBERTS
Keyword(s):  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice

13C spin–lattice relaxation times and molecular motion in N-alkyltetrahydroisoquinoline derivatives

1983 ◽  
pp. 907-910 ◽  
Author(s):  
Makiko Sugiura ◽  
Torei Sai ◽  
Narao Takao ◽  
Hideaki Fujiwara
Keyword(s):  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice

Characterization of Molecular Motion in the Solid State by Carbon-13 Spin–Lattice Relaxation Times

2000 ◽  
Vol 142 (2) ◽  
pp. 229-240 ◽  
Author(s):  
Samuel J Varner ◽  
Robert L Vold ◽  
Gina L Hoatson
Keyword(s):  
Solid State ◽  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice

Molecular motion in the lyotropic liquid crystal system containing potassium palmitate: A study of proton spin-lattice relaxation times

1979 ◽  
Vol 36 (2) ◽  
pp. 151-171 ◽  
Author(s):  
K.R Jeffrey ◽  
T.C Wong ◽  
E.E Burnell ◽  
M.J Thompson ◽  
T.P Higgs ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Lyotropic Liquid Crystal ◽  
Spin Lattice Relaxation ◽  
Crystal System ◽  
Spin Lattice ◽  
Liquid Crystal System

Molecular Motion in Solid Tetraethyl -and Tetrapropylammonium Tetrafluoroborates

1995 ◽  
Vol 50 (6) ◽  
pp. 584-588 ◽  
Author(s):  
Barbara Szafrańska ◽  
Zdzisław Pająk
Keyword(s):  
Molecular Motion ◽  
Solid Phase ◽  
Complex Cation ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Fluorine Nmr ◽  
Spin Lattice ◽  
Second Moments ◽  
Wide Range

Abstract Proton and fluorine NMR second moments and spin-lattice relaxation times for polycrystalline tetraethyl-and tetrapropylammonium tetrafluoroborates have been measured over a wide range of temperatures. Solid-solid phase transitions were found for both compounds and confirmed by DSC. Methyl group C3 reorientation followed by more complex cation motions was evidenced in the low temperature phases. Overall cation reorientation characterises the high temperature phases of both compounds. Isotropic anion reorientation was found in both salts in both phases.

Application of Adiabatic Rapid Passage Nuclear Magnetic Resonance Techniques to the Study of Molecular Motions in Solids

1974 ◽  
Vol 52 (2) ◽  
pp. 191-197 ◽  
Author(s):  
J. A. Ripmeester ◽  
B. A. Dunell
Keyword(s):  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Adiabatic Rapid Passage ◽  
Spin Lattice ◽  
Second Moments ◽  
New Information ◽  
Rotating Frame Relaxation ◽  
Rapid Passage

The adiabatic rapid passage (ARP) technique was applied to the study of molecular motion in solids. Second moments and spin–lattice relaxation times for solid furan and benzene were derived using ARP methods from 77 °K to the respective melting points. Unusual variations of the ARP signal height and shape with temperature were observed for these solids. These effects were interpreted as being due to the presence of short rotating frame relaxation times. New information regarding molecular motion in solid furan, as well as acetic acid-d1, was obtained. Also some quantitative statements have been made regarding the conditions required to observe an ARP signal in the solid state.

A nuclear magnetic resonance investigation of n -pentane, n -hexane and cyclo pentane

1954 ◽  
Vol 222 (1151) ◽  
pp. 526-541 ◽  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Kcal Mole ◽  
Second Moment ◽  
Spin Lattice ◽  
Second Moments

The nuclear magnetic resonance spectra and spin-lattice relaxation times have been measured for the protons in n -pentane (C 5 H 12 ), n -hexane (C 6 H 14 ) and cyclo pentane (C 5 H 10 ) all in the solid state. The temperature range covered was from 70° K to the melting-points of 143·4° K for n -pentane, 177·8° K for n -hexane and 179·4° K for cyclo pentane. In the case of n -pentane and n -hexane the second moments of the absorption lines were found to be smaller than the computed rigid lattice values over the. whole temperature range. Possible molecular motions which might cause this reduction are discussed. It is suggested that the most probable type of motion is reorientation of the methyl groups at the ends of each molecule about the adjacent C—C bonds. An analysis of the spin-lattice relaxation times shows that this reorientation process is governed by an activation energy of 2·7 kcal/mole for n -pentane and 2·9 kcal/mole for n -hexane, values which support the mechanism postulated. At the lowest temperature the absorption lines had not reached their full widths, even though the reorientation frequencies at these temperatures were considerably less than the line-widths. The experimental second moment for cyclo pentane below about 120° K indicates that the lattice is effectively rigid in this temperature region. The uncertainties in both the experimental and theoretical second moments do not allow a distinction to be drawn between the plane and puckered molecular models. At the temperature of the first transition (122·4° K) the line-width second moment and relaxation time all show a sudden decrease. The low value of second moment at the higher temperatures indicates that considerable molecular motion is occurring, the molecules rotating with spherical symmetry. The change in crystal structure at the temperature of the second transition (138·1° K) is thought to be a direct result of this spherical symmetry. As the temperature increases, the results indicate that more molecular motion must be occurring, and it is thought that the rotating molecules are diffusing through the lattice.

Molecular Motion in Tetraphenyltin Studied by NMR

1999 ◽  
Vol 54 (8-9) ◽  
pp. 488-494
Author(s):  
A. Pajzderska ◽  
J. Wąsicki ◽  
S. Lewicki
Keyword(s):  
Phenyl Ring ◽  
Room Temperature ◽  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Ring Rotation ◽  
Phenyl Rings ◽  
Correlated Motion

NMR second moment and spin-lattice relaxation times in the laboratory (60 and 25 MHz) and in therotating frame (B1 = 2.1 mT) were studied for polycrystalline tetraphenyltin Sn(C6H5)4 in a wide temperaturerange. Two kinds of motions were detected: isotropic rotation of whole molecules and reorientations/oscillations of phenyl rings. A dependence of the potential energy of the molecule in the crystalon the angle of the phenyl ring rotation about the Sn-C bond was obtained on the basis of atom-atomcalculations. The amplitude of the ring-oscillations at 133 K was estimated as ± 7°. Below room temperaturethe magnetisation recovery is significantly non-exponential, which may be interpreted as dueto the correlated motion of phenyl rings.

Nuclear Magnetic Resonance Studies of Molecular Motion in Natural Rubber

1963 ◽  
Vol 36 (2) ◽  
pp. 318-324
Author(s):  
W. P. Slichter ◽  
D. D. Davis
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Natural Rubber ◽  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Nmr Studies ◽  
Spin Lattice ◽  
Nuclear Magnetic

Abstract Nuclear magnetic resonance measurements have been made on natural rubber to examine how frequency, temperature, and crystallinity affect the nuclear relaxation. Moecular motions were studied by observing NMR linewidths and spin-lattice relaxation times at temperatures between −100° and 100° C, and at radio frequencies between 2 and 60 Mc. The effect of crystallinity was seen in measurements on stark rubber. The relation between frequency and temperature in the spin-lattice relaxation process is examined in terms of the Arrhenius equation and the WLF expression. The importance of using frequency as a variable in NMR studies of molecular motion is stressed.

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