Chemically Induced Dynamic Nuclear Polarization. X. On Effects of Nuclear Relaxation and the Magnetic Field Dependence

1972 ◽  
Vol 27 (8-9) ◽  
pp. 1300-1307 ◽  
Author(s):  
M. Lehnig ◽  
H Fischer
Keyword(s):  
Magnetic Field ◽  
Field Dependence ◽  
Magnetic Field Dependence ◽  
Nuclear Polarization ◽  
Radical Pair ◽  
Reaction Products ◽  
Theory Analysis ◽  
Alkyl Radicals ◽  
Chemically Induced ◽  
The Magnetic Field

Abstract The magnetic field dependence of CIDNP is presented for two reaction products of independently generated alkyl radicals. It is shown that nuclear spin relaxation of the products influences the intensity distributions within multiplets, and how this relaxation can be included in the calculation of CIDNP effects from the radical pair theory. Analysis of the experimental results supports the recent view that CIDNP is created in pairs of radicals which undergo many diffusive displacements before reencounter.

Chemisch induzierte Kernpolarisation von Phenylhalogeniden bei der Photolyse von Aroylperoxiden

1969 ◽  
Vol 24 (11) ◽  
pp. 1771-1778 ◽  
Author(s):  
M. Lehnig ◽  
H. Fischer
Keyword(s):  
Magnetic Field ◽  
Field Dependence ◽  
Dynamic Nuclear Polarization ◽  
Nmr Spectra ◽  
Magnetic Field Dependence ◽  
Nuclear Polarization ◽  
Radical Reactions ◽  
Chemically Induced ◽  
Polarization Mechanism ◽  
The Magnetic Field

Abstract By a flow technique chemically induced nuclear polarization is observed in the NMR-spectra of phenylhalides formed during photolysis of aroylperoxides in solution. The main features of the polarization are quantitatively explained by dynamic nuclear polarization (CIDNP) of protons in the intermediate phenyl radicals. Some details however indicate that a second polarization mechanism is also present. This mechanism leads to a multiplet-effect type polarization and operates presumably during bond fromation in the radical reactions. Some results on the magnetic field dependence of the nuclear polarizations are given.

The magnetic field dependence of the low temperature (0.1K to 3K) residual specific heat of Pr2−x Ce x CuO4−δ

1996 ◽  
Vol 46 (S3) ◽  
pp. 1213-1214 ◽  
Author(s):  
T. E. Hargreaves ◽  
J. Akimitsu ◽  
D. F. Brewer ◽  
N. E. Hussey ◽  
H. Noma ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Specific Heat ◽  
Field Dependence ◽  
Magnetic Field Dependence ◽  
The Magnetic Field

scholarly journals Exploration of the close chemical space of tryptophan and tyrosine reveals importance of hydrophobicity in CW-photo-CIDNP performances

2021 ◽  
Vol 2 (1) ◽  
pp. 321-329
Author(s):  
Felix Torres ◽  
Alois Renn ◽  
Roland Riek
Keyword(s):  
Magnetic Field ◽  
Nuclear Polarization ◽  
Continuous Wave ◽  
Radical Pair ◽  
Chemical Space ◽  
Spin Dynamics ◽  
Basic Mechanism ◽  
Chemical Library ◽  
Chemically Induced ◽  
Small Chemical

Abstract. Sensitivity being one of the main hurdles of nuclear magnetic resonance (NMR) can be gained by polarization techniques including chemically induced dynamic nuclear polarization (CIDNP). Kaptein demonstrated that the basic mechanism of the CIDNP arises from spin sorting based on coherent electron–electron nuclear spin dynamics during the formation and the recombination of a radical pair in a magnetic field. In photo-CIDNP of interest here the radical pair is between a dye and the molecule to be polarized. Here, we explore continuous-wave (CW) photo-CIDNP (denoted CW-photo-CIDNP) with a set of 10 tryptophan and tyrosine analogues, many of them newly identified to be photo-CIDNP active, and we observe not only signal enhancement of 2 orders of magnitude for 1H at 600 MHz (corresponding to 10 000 times in measurement time) but also reveal that polarization enhancement correlates with the hydrophobicity of the molecules. Furthermore, the small chemical library established indicates the existence of many photo-CIDNP-active molecules.

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