Electron paramagnetic resonance study of the reactions of the spin trap 2,4,6-tribromonitrosobenzene in benzene solutions

1992 ◽  
Vol 70 (1) ◽  
pp. 116-120 ◽  
Author(s):  
Peter Smith ◽  
Kirk Randall Maples ◽  
Ramona Lillian Lau

By means of static-sample studies involving the thermal decomposition of symmetric azo compounds and the oxidation of substrates with nickel peroxide, we have characterized by electron paramagnetic resonance 12 spin adducts of 2,4,6-tribromonitrosobenzene, 1, in benzene at 25 °C. In addition, we have used electron paramagnetic resonance spectroscopy to investigate benzene solutions of 1 both by itself and in the presence of olefins, and both in the presence and absence of light. Although 1 by itself did not give evidence for any free radical formation, when 1 was mixed with any one of the 11 olefins tested we could detect nitroxide formation. The presence of light did not affect our results. These observations support the "ene" reaction mechanism of nitroxide formation. Keywords: 2,4,6-tribromonitrosobenzene, spin trapping, nickel peroxide.


1999 ◽  
Vol 592 ◽  
Author(s):  
Jean-Louis Cantin ◽  
Hans Jurgen von Bardeleben

ABSTRACTThe modification of the Si(001)/SiO2 interface and the related interface defect reduction by thermal treatments in nitric oxide (NO) have been studied by Electron Paramagnetic Resonance spectroscopy for 630Å thick and ultrathin (28Å) oxides. The effects of annealing temperature, annealing time and rapid (RTN) or furnace annealing have been explored. Our results show that an appropriate NO treatment can drastically reduce the defect densities if, in addition to N incorporation in the transition layer near the interface, the thermal relaxation of the nitrided oxide is allowed. Our results indicate that NO treatment can lead to “defect free” Si/SiO2 interfaces.



1998 ◽  
Vol 547 ◽  
Author(s):  
C. Canevali ◽  
N. Chiodini ◽  
F. Morazzoni ◽  
R. Scotti

AbstractSnO2, Ru/SnO2 and Pt/SnO2 were prepared by sol-gel condensation method. Ru/SnO2 was also obtained by supporting the metal on SnO2 xerogel. The reactivity of these materials towards CO and air, studied by Electron Paramagnetic Resonance spectroscopy (EPR), suggests that the electron transfer processes at the oxide surface are favored by the presence of the metal, in the order Pt > Ru ion-exchanged > Ru-supported. A rationale was given for the differences and for the choice of a material suitable to high sensitivity gas sensors.



1993 ◽  
Vol 71 (6) ◽  
pp. 809-813 ◽  
Author(s):  
Peter Smith ◽  
Cynthia Ann Hougum ◽  
Art Aresh Hosseinian

Using the TiCl3–H2O2, –NH2OH, −Na2S2O8, and −H2O2/Na2SO3, continuous-flow, radical-generating methods at 25 °C, we have successfully characterized by electron paramagnetic resonance spectroscopy radicals formed by the reaction of each of the substrates 2- and 3-fluoropropene with the radicals •OH, •NH3+, •OSO3−, and •SO3−, respectively. With 2-and 3-fluoropropene, respectively, the radicals identified were of general formula CH2(X)ĊFCH3 and CH2(X)ĊHCH2F where -X is the added group, except that treatment of 3-fluoropropene with the TiCl3–H2O2 reaction system also yielded •CH2CH(X)CH2F. The results obtained are discussed in terms of the effect of the presence of the fluorine substituent on both the apparent reactivity of the substrate molecules towards the radical-generating systems and the spectroscopic properties of the radicals observed.





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