Etude par résonance paramagnétique électronique de la radiolyse en phase solide de composés cycliques perfluorés

1970 ◽  
Vol 48 (3) ◽  
pp. 435-446 ◽  
Author(s):  
Claude Chachaty ◽  
Alain Forchioni ◽  
Masaru Shiotani
Keyword(s):  
Electron Spin Resonance ◽  
Solid State ◽  
Relative Intensity ◽  
Transition Point ◽  
Γ Irradiation ◽  
Ring Inversion ◽  
Spin Resonance ◽  
The Matrix ◽  
Γ Rays ◽  
Transition Points

Perfluorocyclohexane (PFCH) and perfluoromethylcyclohexane (PFMCH) have been irradiated in the solid state by γ rays of 60Co. The electron spin resonance (e.s.r.) spectrum of PFCH irradiated at 77 °K corresponds mainly towhich is tumbling in the matrix above 160 °K and disappears at the transition point (180 °K). When γ irradiation is carried out at 200 °K, C6F11• is also produced, but reacts with PFCH giving a radicalsupposed to be [Formula: see text]The e.s.r. spectrum of PFMCH γ irradiated at 77 °K has not been identified; it might be attributable in part to (•C6F11CF3)−. Above 160–170° K, the e.s.r. spectrum corresponds only toThe equal coupling of the four γ fluorines and also the relative intensity 1:4:1 of the three main groups of lines observed above 210 °K suggest that ring inversion occurs with a high rate.We have also studied the radicals [Formula: see text]produced by γ irradiation in the presence of oxygen. The variation of their spectra with temperature, particularly near the transition points, is very characteristic of the motion involved.

ELECTRON SPIN RESONANCE STUDIES OF THE RADIATION-INDUCED ADDITION OF HBr TO C2H4 IN THE SOLID STATE

1960 ◽  
Vol 38 (5) ◽  
pp. 689-696 ◽  
Author(s):  
F. W. Mitchell ◽  
B. C. Green ◽  
J. W. T. Spinks
Keyword(s):  
Electron Spin Resonance ◽  
Reaction Mechanism ◽  
Solid State ◽  
Liquid Nitrogen ◽  
Electron Spin ◽  
Reaction Intermediates ◽  
Γ Irradiation ◽  
Solid Mixture ◽  
Spin Resonance ◽  
Radiation Induced

Electron spin resonance measurements at 77 °K have been used to study the hydrobromination of ethylene induced by γ irradiation of the solid mixture at liquid nitrogen temperatures. The evidence resulting from these studies has given valuable information regarding the reaction intermediates and has been used in formulating a likely reaction mechanism.

Electron spin resonance observations on trapped electrons and free radicals formed in olefins at 77 °K by γ-irradiation

1967 ◽  
Vol 45 (8) ◽  
pp. 833-837 ◽  
Author(s):  
D. R. Smith ◽  
F. Okenka ◽  
J. J. Pieroni
Keyword(s):  
Free Radicals ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Hydrogen Abstraction ◽  
Γ Irradiation ◽  
Trapped Electrons ◽  
Spin Resonance ◽  
The Matrix ◽  
Subsequent Exposure ◽  
Branched Chain

Electron spin resonance (e.s.r.) methods have been used to search for the γ-ray-induced formation of trapped electrons and free radicals in 13 straight-chain and branched-chain terminal olefins at 77 °K. When e.s.r. spectra were observed they were used to identify the species present. Changes induced by subsequent exposure to visible and ultraviolet (u.v.) light were investigated. Trapped electrons were observed in three olefins that exist as glasses at 77 °K, hexene-1, hexene-2, and 2-methylbutene-1, but were not detected in two other glassy olefins, possibly because of rapid annealing. No trapped electrons were found in polycrystalline olefins at 77 °K. The possibility that CO2− ions have been misinterpreted as trapped electrons in these and other systems is discussed and eliminated. The formation and behavior of free radicals and trapped electrons in irradiated 2-methylbutene-1 are analogous to those previously reported for 2-methylpentene-1 under similar conditions. These observations support the hypothesis that in these two systems ions produced initially isomerize rapidly, leading to the formation of the free radicals detected by e.s.r. The results of a subsidiary experiment suggest that hydrogen abstraction from the matrix is induced by u.v. photolysis of the radicals present in 2-methylpentene-1.

Light-induced reversible ionization of tetramethylphenylenediamine in an inorganic polymer of n-butyl orthotitanate

1988 ◽  
Vol 66 (8) ◽  
pp. 1931-1935
Author(s):  
Hisashi Ueda ◽  
Masahiro Kaise
Keyword(s):  
Relaxation Time ◽  
Electron Spin Resonance ◽  
Visible Light ◽  
Relative Intensity ◽  
Hyperfine Splitting ◽  
Resonance Absorption ◽  
Spin Quantum ◽  
Spin Quantum Number ◽  
Spin Resonance ◽  
Intensity Ratios

n-Butyl orthotitanate, BT, polymerized in tetrahydrofuran, if irradiated by visible light, gives a new electron spin resonance absorption that is not found before irradiation. In the present work, three different polymers of BT were synthesized by adding tetramethyl phenylenediamine (TMPD), dimethyl phenylenediamine (DMPD), or phenylenediamine (PD), to the solution of BT. The polymers thus prepared were tested to see if they give a new esr signal when irradiated by visible light. The polymer to which 1 mol% of TMPD was added gave TMPD•+ when irradiated by visible light, but the TMPD•+ signal decayed after the irradiation was discontinued. This change, therefore, is reversible. The resonant position of every hyperfine splitting line of the TMPD•+ found in this polymer coincided with that of TMPD•+ in solution, but the relative intensity ratios and the line width of each line depended on the nuclear spin quantum number of the coupling nuclei. This can be interpreted by the restricted rotational motion of TMPD•+ in the polymer matrix. The contribution of the non-diagonal term to the spin relaxation time would explain this phenomenon. In the case of the polymer to which DMPD was added, a small amount of DMPD•+ seemed to be formed, but no radical was detected in the case of the polymer to which PD was added.

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