Photochemistry of propionaldehyde in solution studied by electron spin resonance and CIDNP [chemically induced dynamic nuclear spin polarization]

1973 ◽  
Vol 95 (23) ◽  
pp. 7586-7592 ◽  
Author(s):  
Holger E. Chen ◽  
Shiv P. Vaish ◽  
Michael. Cocivera
Keyword(s):  
Electron Spin Resonance ◽  
Spin Polarization ◽  
Electron Spin ◽  
Nuclear Spin ◽  
Nuclear Spin Polarization ◽  
Chemically Induced ◽  
Spin Resonance

Chemically Induced Dynamic Nuclear Polarization During Irradiation of Phenol in the Presence of Amides

1975 ◽  
Vol 53 (16) ◽  
pp. 2459-2464
Author(s):  
Shiv P. Vaish ◽  
Holger E. Chen ◽  
Micha Tomkiewicz ◽  
Robert D. McAlpine ◽  
Michael Cocivera
Keyword(s):  
Carbonyl Group ◽  
Spin Polarization ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Spin ◽  
Nuclear Polarization ◽  
Radical Pair ◽  
Hydroxybenzoic Acid ◽  
Nuclear Spin Polarization ◽  
Ph Values ◽  
Chemically Induced

Irradiation of D2O solutions containing various phenols with aliphatic amides at pH values between 9 and 12 results in nuclear spin polarization which is observed as n.m.r. emission signals during irradiation. No polarization is observed for the phenols which include tyrosine, cresol, p-hydroxybenzoic acid, phenol, and others. For the amides which include acetamide, propionamide, N-methylacetamide, and N,N-dimethylacetamide, polarization was observed for only the protons on the carbon bonded to the carbonyl group. Because excited phenolate ions are known to eject electrons, it is proposed that the radical RĊ(O−)NR2 is formed by reaction of the amide with the hydrated electron. The polarization observed for the amides can be explained by reaction of RĊ(O−)NR2 with a benzosemiquinone radical via a radical pair.

Electronic Structure of Si-Si Bond in Si3n4 and Sio2: Experiment and Simulation by Mindo/3

1996 ◽  
Vol 446 ◽  
Author(s):  
V.A. Gritsenko ◽  
A.D. Milov ◽  
Yu.N. Morokov ◽  
Yu.N. Novikov ◽  
H. Wong ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Electron Spin Resonance ◽  
Spin Polarization ◽  
Electron Spin ◽  
Resonance Tunneling ◽  
Antiferromagnetic Ordering ◽  
Deep Traps ◽  
Spin Resonance ◽  
Made In ◽  
Localized Electrons

AbstractThe trapping properties of the Si-Si bond in Si3N4 and SiO2 were investigated. The MINDO/3 calculations show that the spin polarization of the Si-Si bond with a captured hole takes place in both SiO2 and Si3N4. The ESR (Electron Spin Resonance) measurements were made in Si3N4 with captured electrons and holes. The number of localized carriers was of two orders of magnitude larger than that used by others. The ESR signal of localized electrons and holes was not observed. A new mechanism of the antiferromagnetic ordering of localized electrons and holes in an insulator with a large concentration of traps is proposed. According to this mechanism, the antiferromagnetic ordering in Si3N4 may be caused by the resonance tunneling of localized spins through nonoccupied traps. We believe that the deep traps responsible for the electron and hole capturing in Si3N4 are the Si-Si bonds.

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