Properties of micellar solutions. Part 4.—Spin lattice relaxation times of hydrocarbon chain protons in solutions of sodium alkyl sulphates

1965 ◽  
Vol 61 (0) ◽  
pp. 1276-1282 ◽  
Author(s):  
J. Clifford
Keyword(s):  
Relaxation Times ◽  
Lattice Relaxation ◽  
Hydrocarbon Chain ◽  
Spin Lattice Relaxation ◽  
Micellar Solutions ◽  
Spin Lattice

13C Fourier transform nuclear magnetic resonance. XII. Structure of the phytol–lecithin bilayer. Application of electric field effects

1976 ◽  
Vol 54 (13) ◽  
pp. 2059-2067 ◽  
Author(s):  
Robert J. Cushley ◽  
Bruce J. Forrest
Keyword(s):  
Electric Field ◽  
Chemical Shifts ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Hydrocarbon Chain ◽  
Spin Lattice Relaxation ◽  
Head Group ◽  
Electric Field Effect ◽  
Spin Lattice ◽  
Lipid Head Group

Phytol has been incorporated into lecithin bilayers. 13C spin–lattice relaxation times, which have been measured for both components of the model membrane, indicate a marked destabilization of the bilayer due to intercalated phytol. The disruption of normal phospholipid packing is due to the highly branched nature of the phytyl hydrocarbon chain. In addition, the position of phytol in the bilayer has been determined by means of a linear electric field effect of the polar lipid head group upon the 13C chemical shifts of the phytol olefinic carbons.

A determination of the mobility gradient in lipid bilayers by 13 C nuclear magnetic resonance

1976 ◽  
Vol 193 (1112) ◽  
pp. 253-274 ◽  
Keyword(s):  
Lipid Bilayers ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Hydrocarbon Chain ◽  
Phospholipid Bilayers ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Hydrocarbon Chains ◽  
Carbon Carbon Bonds ◽  
Carbon Bonds

The spin-lattice relaxation times of individual 13 C nuclei in phospholipid bilayers have been measured by using both natural-abundance 13 C and selectively 13 C-enriched phospholipids. These relaxation times can be analysed to give values for the diffusion coefficients for motion about individual carbon-carbon bonds, and for motion about the long axis of the hydrocarbon chains in the bilayer. The assumptions involved in this analysis are examined, and the values obtained compared with those for n -alkanes, and with the results of studies of molecular motion in lipid bilayers by other methods. The results indicate that motion about carbon-carbon bonds in phospholipid bilayers is relatively rapid, and emphasize the fluid nature of the hydrocarbon chain region of such bilayers. This picture of the bilayer is compared with that obtained by techniques which measure time-average conformational properties of the hydrocarbon chains in the bilayer.

Bonded Hydrogen and Trapped H2 in a-Si1−xGex:H Alloys

1989 ◽  
Vol 149 ◽  
Author(s):  
E. J. Vanderheiden ◽  
G. A. Williams ◽  
P. C. Taylor ◽  
F. Finger ◽  
W. Fuhs
Keyword(s):  
Temperature Dependence ◽  
Molecular Hydrogen ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
H Nmr ◽  
Local Environments

ABSTRACT1H NMR has been employed to study the local environments of bonded hydrogen and trapped molecular hydrogen (H2) in a series of a-Si1−xGex:H alloys. There is a monotonic decrease of bonded hydrogen with increasing x from ≈ 10 at. % at x = 0 (a-Si:H) to ≈ 1 at. % at x = 1 (a-Ge:H). The amplitude of the broad 1H NMR line, which is attributed to clustered bonded hydrogen, decreases continuously across the system. The amplitude of the narrow 1H NMR line, which is attributed to bonded hydrogen essentially randomly distributed in the films, decreases as x increases from 0 to ≈ 0.2. From x = 0.2 to x ≈ 0.6 the amplitude of the narrow 1H NMR line is essentially constant, and for x ≥ 0.6 the amplitude decreases once again. The existence of trapped H2 molecules is inferred indirectly by their influence on the temperature dependence of the spin-lattice relaxation times, T1. Through T1, measurements it is determined that the trapped H2 concentration drops precipitously between x = 0.1 and x = 0.2, but is fairly constant for 0.2 ≤ x ≤ 0.6. For a-Si:H (x = 0) the H2 concentration is ≈ 0.1 at. %, while for x ≥ 0.2 the concentration of H2 is ≤ 0.02 at. %.

Water-Saturated Mesoporous MCM-41 Systems Characterized by 1H NMR Spin-Lattice Relaxation Times

1995 ◽  
Vol 99 (12) ◽  
pp. 4148-4154 ◽  
Author(s):  
Eddy Walther Hansen ◽  
Ralf Schmidt ◽  
Michael Stoecker ◽  
Duncan Akporiaye
Keyword(s):  
1H Nmr ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Water Saturated ◽  
Mcm 41
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