Electron spin resonance of the Mn2+ion in the study of the mobility of water adsorbed on silica gel and γ-alumina

1976 ◽  
Vol 72 (0) ◽  
pp. 324-330 ◽  
Author(s):  
Leo Burlamacchi ◽  
Giacomo Martini ◽  
M. Francesca Ottaviani
Keyword(s):  
Electron Spin Resonance ◽  
Silica Gel ◽  
Electron Spin ◽  
Spin Resonance

Electron Spin Resonance Study of Surface Defects of Silica Gel Formed by Gas Discharges

1971 ◽  
Vol 49 (3) ◽  
pp. 352-356 ◽  
Author(s):  
K. Hukuda ◽  
Y. Amenomiya
Keyword(s):  
Electron Spin Resonance ◽  
Silica Gel ◽  
Electron Spin ◽  
Surface Defects ◽  
Hydroxyl Group ◽  
Electron Spin Resonance Study ◽  
Gas Discharges ◽  
Spin Resonance ◽  
Magnetic Center ◽  
Spin Resonance Study

Surface defects of silica gel formed by a microwave electric discharge in a stream of oxygen and of nitrogen have been studied by means of electron spin resonance (e.s.r.) spectroscopy. The magnetic center is identified as a hole trapped by a surface oxygen atom which is formed by the removal of a hydrogen atom from a hydroxyl group. The principal values of the g-tensor were found to be gxx = 2.037, gyy = 2.008, and gzz = 2.002, respectively, where the direction of x-axis was taken along the O—Si bond. The center has a weak hyperfine interaction with a hydrogen nucleus of an adjacent hydroxyl group. The hyperfine splitting is 15 Oe.

Electron Spin Resonance Studies of the Radiolysis of Aliphatic Amines Adsorbed on Silica Gel

1971 ◽  
Vol 49 (11) ◽  
pp. 1880-1887 ◽  
Author(s):  
P. Wardman ◽  
D. R. Smith
Keyword(s):  
Electron Spin Resonance ◽  
Silica Gel ◽  
Electron Spin ◽  
Active Site ◽  
Cation Radical ◽  
Aliphatic Amines ◽  
Polycrystalline Solid ◽  
Spin Resonance ◽  
Butyl Amine ◽  
Surface Active

Several aliphatic amines have been adsorben in sub-monolayer amounts on silica gel and γ-irradiated at 77 °K. The electron spin resonance (e.s.r.) spectra of the radicals trapped on the surface at 77 °K were similar, in most cases, to the spectra obtained after irradiating the corresponding polycrystalline solid amine at 77 °K. Methyl-, ethyl-, n-propyl, and n-butylamines all gave [Formula: see text] radicals, and dimethylamine gave [Formula: see text] radicals. The radical cation [Formula: see text] was observed in the case of trimethylamine. Adsorbed methoxy-amine and t-butyl amine have also been studied and the cation-radical of the latter tentatively identified. The results are discussed in terms of reaction of the adsorbed amine with a surface active site.

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