Temperature‐dependent ESR hyperfine constants for nitroxides and orientational correlation time determination

1984 ◽  
Vol 81 (10) ◽  
pp. 4206-4209 ◽  
Author(s):  
Sook Lee ◽  
D. P. Ames
Keyword(s):  
Correlation Time ◽  
Temperature Dependent ◽  
Hyperfine Constants ◽  
Time Determination ◽  
Orientational Correlation

A novel 1:1 benzenesulfonamide: 18-crown-6 complex as uncovered via 13C solid phase NMR spectroscopy and X-ray crystallography

1989 ◽  
Vol 67 (7) ◽  
pp. 1212-1218 ◽  
Author(s):  
G. W. Buchanan ◽  
C. Morat ◽  
J. P. Charland ◽  
C. I. Ratcliffe ◽  
J. A. Ripmeester
Keyword(s):  
Crown Ether ◽  
Correlation Time ◽  
Molecular Motion ◽  
Solid Phase ◽  
Crystallographic Structure ◽  
Temperature Dependent ◽  
X Ray ◽  
X Ray Crystallography ◽  
Anisotropic Motion ◽  
Motional Correlation Time

A 1:1 complex of 18-crown-6 ether and benzenesulfonamide has been prepared, whose melting point is within 4° of the previously reported 1:2 complex. The X-ray crystallographic structure shows pseudo D3d symmetry in the crown ether portion of this complex, in contrast to the 1:2 complex, which exhibits Ci symmetry in the macrocycle. The temperature dependent 13C CPMAS NMR spectra of these complexes have two regions of broadening for the crown ether carbons. At higher temperatures, a dipolar "washout" mechanism is operative, leading to broadening when molecular motion has a correlation time approximately equal to the inverse of the decoupling field. At lower temperatures broadening occurs when the motional correlation time is equal to the inverse of the chemical shift difference. From application of the Arrhenius equation, the activation energy for the molecular motion in solid 18-crown-6 is found to be approximately 10kcal/mol. Evidence for independent anisotropic motion in the benzenesulfonamide moiety of the 1:1 complex is also presented. Keywords: crown ether, molecular motion, solid phase NMR.

The orientational‐correlation time intercept in liquids

1986 ◽  
Vol 84 (1) ◽  
pp. 385-390 ◽  
Author(s):  
Glenn T. Evans ◽  
Daniel Kivelson
Keyword(s):  
Correlation Time ◽  
Orientational Correlation

(111) Monocrystalline Nickel Films

1972 ◽  
Vol 30 ◽  
pp. 512-513
Author(s):  
T.E. Pratt ◽  
R.W. Vook
Keyword(s):  
Film Thickness ◽  
Deposition Rate ◽  
Room Temperature ◽  
Narrow Range ◽  
High Vacuum ◽  
Residual Pressure ◽  
Temperature Dependent ◽  
Deposition Parameters ◽  
Transmission Electron ◽  
Substrate Temperatures

(111) oriented thin monocrystalline Ni films have been prepared by vacuum evaporation and examined by transmission electron microscopy and electron diffraction. In high vacuum, at room temperature, a layer of NaCl was first evaporated onto a freshly air-cleaved muscovite substrate clamped to a copper block with attached heater and thermocouple. Then, at various substrate temperatures, with other parameters held within a narrow range, Ni was evaporated from a tungsten filament. It had been shown previously that similar procedures would yield monocrystalline films of CU, Ag, and Au.For the films examined with respect to temperature dependent effects, typical deposition parameters were: Ni film thickness, 500-800 A; Ni deposition rate, 10 A/sec.; residual pressure, 10-6 torr; NaCl film thickness, 250 A; and NaCl deposition rate, 10 A/sec. Some additional evaporations involved higher deposition rates and lower film thicknesses.Monocrystalline films were obtained with substrate temperatures above 500° C. Below 450° C, the films were polycrystalline with a strong (111) preferred orientation.

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