Proton NMR Studies of Amorphous Plasma-Deposited Films

1980 ◽  
Vol 3 ◽  
Author(s):  
Jeffrey A. Reimer ◽  
Robert W. Vaughan ◽  
John C. Knights

ABSTRACTProton magnetic resonance data are presented for the hydrogen alloys of plasma-deposited amorphous boron, silicon, carbon, silicon carbide, and silicon nitride. Linewidth and lineshape analysis leads to the conclusion that hydrogen nuclei are clustered in a-Si/C:H, a-C:H, and a-Si/NiH. The a-Si/C:H and a-C:H data show that hydrogen exists in two phases. Modeling of linewidths in a-Si/C:H indicates that the two phases are heavily hydrogenated carbon clusters imbedded in a weakly hydrogenated silicon lattice. Evidence is also presented for the presence of motionally narrowed hydrogen spectra in a-B:H, a-Si/N:H and a-C:H. “B NMR spectra in a-B:H show no evidence of motional narrowing. It is suggested that the hydrogen nuclei giving rise to the motionally narrowed spectra are associated with disorder modes.

1991 ◽  
Vol 69 (7) ◽  
pp. 1156-1160 ◽  
Author(s):  
Tahar Lakhlifi ◽  
Ahmed Sedqui ◽  
Bernard Laude ◽  
Nguyen Dinh An ◽  
Joël Vebrel

Three azomethine ylide precursors including the methyl 3,4-dihydro-6,7-dimethoxyisoquinoline-3carboxylate moiety were synthesized. The 1,3-dipolar species formed from these products react with activated dipolarophilic olefines leading diastereospecifically to derivatives of 4′,5′-dimethoxy-1,2-benzo-4,7-imino-4-methoxycarbonyl-1-cycloheptene. Proton magnetic resonance data allowed the determination of the stereochemistry of the cycloadducts. Key words: cyclic azomethine ylide, azabicyclic compounds, stereochemistry.


1973 ◽  
Vol 51 (15) ◽  
pp. 2571-2577 ◽  
Author(s):  
Donald J. Wood ◽  
Frank E. Hruska ◽  
Richard J. Mynott ◽  
Ramaswamy H. Sarma

Proton magnetic resonance data for uridine and uridine-5′-monophosphate, and the corresponding 6-azauracil analogs, are presented and discussed in terms of their overall three dimensional conformations in aqueous solution. The data reveal a destabilizing influence of the 6-aza base upon the gog and g′–g′ conformation of the ribose phosphate moiety.


1980 ◽  
Vol 34 (5) ◽  
pp. 575-578 ◽  
Author(s):  
Shigetaka Shimada ◽  
Takeshi Tanigawa ◽  
Hisatsugu Kashiwabara

Distribution of the correlation time in solid polymers was taken into consideration in the analysis of the magnetic resonance data. Motional narrowing of the line width of the EPR spectrum of fluoroalkyl radicals in polytetrafluoroethylene and that of broad line NMR spectrum (fluorine resonance) were observed on the same samples at the temperatures ranging from 260 to 320K. Since EPR and NMR measurements are measurements with different characteristic times of observation, representative correlation times corresponding to respective measurements were found to agree with the relaxation theory proposed by Miyake [J. Polym. Sci. 28: 476 (1958)] in which distributions of correlation time were taken into consideration. Based on these values, the real activation energy of the molecular motion associated with the motional narrowings of EPR and NMR studies were found to be 310 KJ/mol. On the other hand, the activation energy which gives the same relaxation spectrum as obtained from EPR and NMR data was found to be 318 KJ/mol. This reflects that the analysis in the present paper is a proper analysis. The present paper presents an example in which the consideration of the distribution of the correlation time was successfully applied.


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