Determination of the population, depopulation and the anisotropic spin lattice relaxation rates in the photoexcited triplet state of phenazine. A light modulation-EPR study

1975 ◽  
Vol 36 (3) ◽  
pp. 377-381 ◽  
Author(s):  
Uzi Eliav ◽  
Haim Levanon
Keyword(s):  
Triplet State ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Light Modulation ◽  
Relaxation Rates ◽  
Spin Lattice

An experimental evaluation of simplified procedures for determining the proton spin–lattice relaxation rates of natural products

1980 ◽  
Vol 58 (19) ◽  
pp. 2016-2023 ◽  
Author(s):  
Lawrence D. Colebrook ◽  
Laurance D. Hall
Keyword(s):  
Natural Products ◽  
Lattice Relaxation ◽  
Null Point ◽  
Proton Spin ◽  
Computational Method ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Spin Lattice ◽  
Simplified Procedures

A general discussion is given of the determination of the proton spin–lattice relaxation rates of natural products, with particular emphasis on use of the null-point method which, for the systems studied here, gives identical results with those obtained via the conventional (and relatively time consuming) computational method.

13 C n.m.r. in organic solids: limits to spectral resolution and to determination of molecular motion

1981 ◽  
Vol 299 (1452) ◽  
pp. 609-628 ◽  
Keyword(s):  
Lattice Relaxation ◽  
Spectral Lines ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Organic Solids ◽  
Spin Lattice ◽  
Fundamental Limitations ◽  
The Status ◽  
History Of

The history of high-resolution n.m.r. in solids has been, inter alia , a quest for narrow spectral lines. Yet, with few exceptions, solid state resonances have not been sharpened to the degree of liquid resonances. To aid in the appraisal of the status of n.m.r. in solids, we identify and summarize, for the particular case of 13 C n.m.r. in organic solids, those effects that can degrade resolution. Some of these mechanisms are under the experimenter’s control; for example, certain are exacerbated at high magnetic field. Others, however, represent fundamental limitations imposed by the specimen and are valid reflections of the complexity of a solid as contrasted to a liquid. In solids, magnetic dipolar spin-spin couplings can not only degrade resolution but also complicate, hopelessly in some cases, the determination of spin-lattice relaxation rates from which one seeks information about molecular motions. The consequences of this competition between spin-spin and spin-lattice effects are examined, as well as criteria and strategies to isolate the motional contributions to relaxation rates.

Proton Relaxation in Various Copper (II) Complexes and Determination of the Singlet-Triplet Separation

1980 ◽  
Vol 35 (1) ◽  
pp. 92-97 ◽  
Author(s):  
H. D. Jannek ◽  
W. Midler-Warmuth
Keyword(s):  
Copper Complexes ◽  
Lattice Relaxation ◽  
Magnetic Behaviour ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Proton Relaxation ◽  
Relaxation Rates ◽  
Temperature Dependent ◽  
Spin Lattice

Abstract Proton spin-lattice relaxation rates have been measured at 30 MHz as a function of temperature for a large number of dimeric copper complexes with the ligands 8-hydroxyquinoline, pyridine-N-oxide, methyl and dimethyl pyridine-N-oxide, and quinoline-N-oxide. Two carboxylates and adducts of several complexes with various solvents have also been studied. In contrast to some compounds with a normal magnetic behaviour, for most complexes a temperature dependent relaxation has been observed which agrees well with the concept of a weak antiferromagnetic interaction between the two Cu2+ ions. The singlet-triplet separations or exchange integrals have been determined.

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