Nuclear Magnetic Resonance in Hexagonal Lanthanum Metal: Knight Shifts, Spin Relaxation Rates, and Quadrupole Coupling Constants

1969 ◽  
Vol 179 (2) ◽  
pp. 359-367 ◽  
Author(s):  
Albert NARATH
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Spin Relaxation ◽  
Coupling Constants ◽  
Relaxation Rates ◽  
Quadrupole Coupling ◽  
Knight Shifts ◽  
Nuclear Magnetic

Solid State NMR Measurements for Preliminary Lifetime Assessments in λ-Irradiated and Thermally Aged Siloxane Elastomers

2004 ◽  
Vol 851 ◽  
Author(s):  
Sarah C. Chinn ◽  
Julie L. Herberg ◽  
April M. Sawvel ◽  
Robert S. Maxwell
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Coupling Constants ◽  
Screening Tools ◽  
Engineering Properties ◽  
Relaxation Rates ◽  
Nmr Studies ◽  
Wide Range ◽  
Nuclear Magnetic

ABSTRACTSiloxanes have a wide variety of applications throughout the aerospace industry which take advantage of their exceptional insulating and adhesive properties and general resilience. They also offer a wide range of tailorable engineering properties with changes in composition and filler content. They are, however, subject to degradation in radiatively and thermally harsh environments. We are using solid state nuclear magnetic resonance techniques to investigate changes in network and interfacial structure in siloxane elastomers and their correlations to changes in engineering performance in a series of degraded materials. Nuclear magnetic resonance (NMR) parameters such as transverse (T2) relaxation times, cross relaxation rates, and residual dipolar coupling constants provide excellent probes of changes crosslink density and motional dynamics of the polymers caused by multi-mechanism degradation. The results of NMR studies on aged siloxanes are being used in conjunction with other mechanical tests to provide insight into component failure and degradation kinetics necessary for preliminary lifetime assessments of these materials as well as into the structure-property relationships of the polymers. NMR and magnetic resonance imaging (MRI) results obtained both from high resolution NMR spectrometers as well as low resolution benchtop NMR screening tools will be presented.

A Comparative Nuclear Magnetic Resonance Study of the Solvation of CuClO4 in Binary Mixtures of Acetonitrile with Pyridine and Picolines at 298K

2012 ◽  
Vol 67 (5) ◽  
pp. 303-307 ◽  
Author(s):  
Dip Singh Gill ◽  
Dilbag Singh Rana ◽  
Mohinder Singh Chauhan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Binary Mixtures ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Mixed Complex ◽  
Magnetic Resonance Study ◽  
Quadrupole Coupling ◽  
Ubbelohde Viscometer ◽  
Nuclear Magnetic

63Cu nuclear magnetic resonance (NMR) and viscosity studies of 0:064M CuClO4 solutions have been reported in binary mixtures of acetonitrile (AN) with pyridine (Py) and 2, 3, and 4-picolines (2,3,4-Pic) at 298 K using a Bruker 500 MHz NMR spectrometer and an Ubbelohde viscometer, respectively. Chemical shift d and linewidth D for the 63Cu signals have been recorded referenced to a 0:064M CuClO4 solution in anhydrous AN. The copper quadrupole coupling constants (e2Qq=h) have been calculated in all cases. The variation of the d and e2Qq=h values as a function of mol fraction of the co-solvent show that all these bases interact with Cu+ more strongly than AN. They replace AN from the Cu+ complexed with AN in the form [Cu(AN)4]+ and form a mixed complex of the type [Cu(AN)4-x(S)x]+ (x=1 - 4) where S stands for the base. At relatively high mole fraction of the co-solvents, the mixed solvated complex gradually changes to a more symmetrical complex of the type [Cu(S)4]+ which remains stable in the solution. The solvating effect of 2-Pic and 4-Pic is observed to be stronger than that of Py and 3-Pic.

Quadrupoleffekte der magnetischen Kernresonanz an 11B in Bor-Stickstoffverbindungen

1969 ◽  
Vol 24 (4) ◽  
pp. 566-572 ◽  
Author(s):  
Klaus Wiedemann ◽  
Jürgen Voitländer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Quadrupole Interaction ◽  
Second Order ◽  
Coupling Constants ◽  
Quadrupole Coupling ◽  
Wide Line ◽  
Nuclear Quadrupole ◽  
Asymmetry Parameters ◽  
Nuclear Magnetic

Abstract First and second-order quadrupole effects of the 11B nuclear magnetic resonance have been measured in polycrystalline samples of dimere dimethylaminoboranes and tetramethylboracene. With the theory of powder patterns for first and second-order quadrupole interaction the nuclear quadrupole coupling constants e2 q Q/h and asymmetry parameters η of 11B have been determined. For these measurements boron-free inserts had to be constructed for the probes of the Varian Wide Line Spectrometer DA 60.

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