Direct Determination of15N- and19F-NMR Correlation Times from Spin−Lattice and Spin−Spin Relaxation Times

1998 ◽  
Vol 102 (5) ◽  
pp. 812-815 ◽  
Author(s):  
W. Robert Carper ◽  
Evangelos A. Nantsis
Keyword(s):  
Spin Relaxation ◽  
Relaxation Times ◽  
Direct Determination ◽  
Correlation Times ◽  
Spin Lattice

Nuclear magnetic resonance spin–lattice relaxation and the rotation of adamantane and hexamethylenetetramine in solution

1977 ◽  
Vol 55 (13) ◽  
pp. 2564-2569 ◽  
Author(s):  
Roderick E. Wasylishen ◽  
Brian A. Pettitt
Keyword(s):  
Variable Temperature ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Hard Sphere Model ◽  
Correlation Times ◽  
Spin Lattice ◽  
H Nmr ◽  
Large Step ◽  
Resonance Spin

Deuterium nmr spin–lattice relaxation times have been measured for dilute solutions of adamantane-d16 in CH2I2, CHBr3, CCl4, CHCl3, and CH2Cl2. The reorientation correlation times, τ2, calculated from the experimental data are used to calculate τJ, the angular momentum correlation times, assuming both the J-diffusion and Hubbard relations. The derived τJ values suggest that adamantane executes small step diffusion in CH2I2 and CHBr3, and large step diffusion in CCl4, CHCl3, and CH2Cl2. The calculated τJ values do not appear to be related to the mean times between collisions calculated using a hard sphere model. Both variable solvent and variable temperature experiments indicate 1 ps/cP for the viscosity dependence of the adamantane reorientation time, about 1/36th the value predicted using the familiar Stokes–Einstein equation.Carbon-13 and 1H nmr T1 data indicate that reorientation of hexamethylenetetramine in H2O (28 ps/cP), CHCl3 (27 ps/cP), and CHBr3 (18 ps/cP) is severely hindered because of inter-molecular hydrogen bonding.

Relaxationszeiten des Elektronenspins von Radikalen in einigen bestrahlten Aminosäuren bei 4,2 °K

1966 ◽  
Vol 21 (3) ◽  
pp. 296-300 ◽  
Author(s):  
G. Bürk ◽  
G. Schoffa
Keyword(s):  
Amino Acids ◽  
Spin Relaxation ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Electron Spin Relaxation ◽  
Spin Lattice ◽  
Saturation Method ◽  
Rapid Adjustment ◽  
Inhomogeneous Line Broadening

Electron spin relaxation times of the irradiated amino acids acetyl valine, sarcosine, betaine, and glycine have been measured at 4.2 °K with two different methods. From the exponential decrease of signals due to saturation after rapid adjustment of the ESR spectrometer on resonance, the following spin-lattice relaxation times have been measured: acetyl valine T1= 0.2 sec, sarcosine T1=0.14 sec, betaine T1=0.07 sec, glycine T1 ∼ 0.3 sec. By the PORTIS saturation method the product T1 T2 was measured, and, T1 being known, the following spin-spin relaxation times T2 have been obtained: acetyl valine 2.1.10-9sec, sarcosine 1.10-9sec, betaine 9.10-10sec. All measured amino acids show the saturation behaviour of substances with “inhomogeneous” line broadening.

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