Second-order effects observed in the electron spin resonance spectra of methyl radicals stabilised on silica at 77 K

1978 ◽  
pp. 164 ◽  
Author(s):  
Duro Oduwole ◽  
John D. Barnes ◽  
Barrie Wiseall
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Second Order ◽  
Order Effects ◽  
Methyl Radicals ◽  
Spin Resonance ◽  
Second Order Effects

Electron spin resonance studies of methyl radicals stabilized on porous VYCOR glass: various surface interactions, second-order splitting, and a linewidth temperature study

1970 ◽  
Vol 48 (17) ◽  
pp. 2685-2694 ◽  
Author(s):  
G. B. Garbutt ◽  
H. D. Gesser
Keyword(s):  
Electron Spin Resonance ◽  
High Temperature ◽  
Electron Spin ◽  
Second Order ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Potential Wells ◽  
Vycor Glass ◽  
Porous Vycor Glass ◽  
Spin Resonance

Electron spin resonance studies have been performed on methyl radicals stabilized on the surface of porous VYCOR glass. As previously reported, two very different methyl radicals, denoted Me and Me′, were seen. Results indicate that the radical Me′ is most probably weakly bound to the boroxane group (=B—O—B=) which is prominent on the surface of high temperature (700–900 °C) pretreated porous VYCOR glass. Four satellite lines about each Me line, denoted previously as radical X, were observed when the surface was pretreated at lower temperatures (400–500 °C). In an earlier publication radical X was attributed to the interaction between methyl radicals and the isotopic surface species 11B. In this study two additional satellite lines about each Me line are reported as well as a reassignment of the origin of all satellite lines. Four of the six satellite lines have been assigned to forbidden "spin–flip" transitions while the other two have been assigned to direct interaction between methyl radicals and the surface hydroxyl protons. Support for the irreversibility of high temperature dehydroxylation of porous VYCOR glass is also presented.A partial resolution of the second-order splitting of each of the central pair of lines was achieved for the normal methyl radical. The value of the second-order splitting was between 220 and 230 mG. The linewidths of the two central lines were measured at 77 °K. The samples were then allowed to warm up to various temperatures and then recooled to 77 °K. The linewidths were smaller after completing this cycle. Storage of the sample at 77 °K allowed the linewidths to return to their original values. These linewidths effects are explained by postulating the existence of two different types of potential wells on the surface.

The Detection of Alkoxy and Other Radicals in the Gamma Radiolysis of Alcohols by an Electron Spin Resonance and Spin Trapping Method

1974 ◽  
Vol 52 (21) ◽  
pp. 3645-3650 ◽  
Author(s):  
Frederick Peter Sargent ◽  
Edward Michael Gardy
Keyword(s):  
Electron Spin Resonance ◽  
Carbon Atom ◽  
Electron Spin ◽  
Spin Trapping ◽  
Methyl Radicals ◽  
Alkoxy Radicals ◽  
Spin Resonance ◽  
Gamma Radiolysis ◽  
Trapping Method

The radicals produced during γ radiolysis of methanol, ethanol, 1-propanol, 2-propanol, and t-butanol have been trapped by reaction with 2-nitroso-2-methylpropane (t-nitrosobutane) to give nitroxides which are detected by e.s.r.[Formula: see text]All the alcohols gave alkoxy radicals and, with the exception of t-butanol, radicals derived by the loss of an H atom from the carbon atom adjacent to the OH group. Methyl radicals were detected in t-butanol.

Electron spin resonance study of γ-irradiated tetraethylammonium iodide

1968 ◽  
Vol 46 (16) ◽  
pp. 2749-2752 ◽  
Author(s):  
L. Fabes ◽  
J. K. S. Wan
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Secondary Reaction ◽  
Electron Spin Resonance Study ◽  
Methyl Radicals ◽  
Γ Irradiation ◽  
Spin Resonance ◽  
Secondary Radical ◽  
Tetraethylammonium Iodide ◽  
Spin Resonance Study

γ-Irradiation of polycrystalline tetraethylammonium iodide at 77°K leads to the breaking of a C—C bond and the primary radicals ĊH3 and [Formula: see text] were detected by electron spin resonance. The methyl radicals were found to disappear readily at 120°K. In the range of 263–273°K a secondary reaction between [Formula: see text] and the parent ion [Formula: see text] was observed; the resulting secondary radical [Formula: see text] was found to be stable up to 373°K.

Electron Spin Resonance Study on γ-Ray-Induced Methyl Radicals in Methane Hydrates

2004 ◽  
Vol 43 (1) ◽  
pp. 353-357 ◽  
Author(s):  
Kei Takeya ◽  
Atsushi Tani ◽  
Takeshi Yada ◽  
Motoji Ikeya ◽  
Kazunari Ohgaki
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Electron Spin Resonance Study ◽  
Methane Hydrates ◽  
Methyl Radicals ◽  
Spin Resonance ◽  
Γ Ray ◽  
Spin Resonance Study

Methyl "radicals" on doped silica gel surfaces

1969 ◽  
Vol 47 (18) ◽  
pp. 3367-3369 ◽  
Author(s):  
E. J. Casey ◽  
C. W. M. Grant ◽  
C. L. Gardner
Keyword(s):  
Electron Spin Resonance ◽  
Silica Gel ◽  
Electron Spin ◽  
Line Intensity ◽  
Free Electron ◽  
Hyperfine Splitting ◽  
Silica Gels ◽  
Methyl Radicals ◽  
Spin Resonance ◽  
Hot Oxygen

Methyl radicals adsorbed on silica gels containing dopings of the semiconductor ZnO were investigated by electron spin resonance at 77 °K. In addition to the normal 4-line "a"-spectrum, with hyperfine splitting of 23.3 ± 0.2 G, a second broader 4-line spectrum "b" with splitting 18.8 ± 0.6 G appears. Variations in line intensity with extent of doping were measured. Disappearance of the b-spectrum when the doped gels were dried under hot oxygen was observed. Partial delocalization of the radical's free electron and mixing into the doped surface were clearly indicated.Satellites ("c") to the a-spectrum were observed and are discussed.

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