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.

An Electron Spin Resonance Examination of Ferrocenylalkyl- and Aryl Ketyls

1972 ◽  
Vol 50 (12) ◽  
pp. 1825-1830 ◽  
Author(s):  
G. Bigam ◽  
John Hooz ◽  
Siegfried Linke ◽  
R. E. D. McClung ◽  
Melvyn W. Mosher ◽  
...  
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Free Electron ◽  
Hyperfine Splitting ◽  
Electron Densities ◽  
Spin Resonance ◽  
Hyperfine Splittings ◽  
Insight Into

Several ferrocenylalkyl- and aryl ketyls were generated and their e.s.r. spectra were recorded. Pentadeuterio-benzoylferrocene and benzoyl perdeuterioferrocene were synthesized. Analysis of the e.s.r. spectra of their corresponding ketyls enabled the determination of the hyperfine splitting constants of benzoylferrocene ketyl, and allowed an assignment of the electron densities at various positions in the molecule.A comparison of the magnitudes of the g-values for the ketyls derived from benzophenone (2.0034), benzoylferrocene (2.0062), and 2,2-dimethylpropanoylferrocene (2.0126), combined with the proton hyperfine splittings, gave some insight into the nature of the interaction of the free electron with the ferrocene system.

Tumbling of methyl radicals adsorbed on a silica gel surface studied by electron spin resonance

1968 ◽  
Vol 46 (2) ◽  
pp. 207-210 ◽  
Author(s):  
C. L. Gardner ◽  
E. J. Casey
Keyword(s):  
Electron Spin Resonance ◽  
Silica Gel ◽  
Electron Spin ◽  
Relaxation Mechanism ◽  
Quantitative Comparison ◽  
Methyl Radicals ◽  
Spin Quantum ◽  
Spin Quantum Number ◽  
Spin Resonance ◽  
Marked Dependence

The electron spin resonance spectra of CH3 and CD3 adsorbed on a silica gel surface at 77 °K are characterized by a marked dependence of the line width on nuclear spin quantum number. This dependence can be interpreted in terms of the tumbling of the radicals on the surface, anisotropies in the hyperfine and g tensors giving rise to a relaxation mechanism dependent on MI. A quantitative comparison of the spectra with the theory of this relaxation mechanism developed by McConnell, Kivelson, and Freed and Fraenkel enables the tumbling frequencies, 2.0 × 107 s−1 and 1.3 × 107 s−1 for CH3 and CD3 respectively, to be determined.

Correlation of optical and electron spin resonance spectra for alkali metal solutions in ethylamine and tetrahydrofuran

1976 ◽  
Vol 54 (19) ◽  
pp. 3110-3113 ◽  
Author(s):  
R. Catterall ◽  
J. Slater ◽  
W. A. Seddon ◽  
J. W. Fletcher
Keyword(s):  
Electron Spin Resonance ◽  
Optical Absorption ◽  
Alkali Metal ◽  
Electron Spin ◽  
Hyperfine Splitting ◽  
Pulse Radiolysis ◽  
Optical Absorption Spectra ◽  
Monomeric Species ◽  
Spin Resonance ◽  
Sodium Tetraphenylboron

The band maxima of transient optical absorption spectra observed by pulse radiolysis in ethylamine (EA)/tetrahydrofuran (THF) mixtures containing sodium tetraphenylboron are correlated with electron spin resonance (esr) hyperfine splitting constants obtained in potassium/EA/THF solutions. The data suggest that the optical spectra can be attributed to the same 'monomeric' species as observed by esr in alkali metal solutions.

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