MEASUREMENT OF ELECTRON SPIN RESONANCE DIFFERENCE SPECTRA AT 77 °K: APPLICATIONS OF THE METHOD IN LOW-TEMPERATURE RADIATION CHEMISTRY

1964 ◽  
Vol 42 (10) ◽  
pp. 2209-2214 ◽  
Author(s):  
D. R. Smith ◽  
J. J. Pieroni
Keyword(s):  
Electron Spin Resonance ◽  
Hydrogen Atom ◽  
Low Temperature ◽  
Electron Spin ◽  
Radiation Chemistry ◽  
Paramagnetic Species ◽  
Difference Spectra ◽  
Silica Sample ◽  
Spin Resonance ◽  
Temperature Radiation

The technique of measuring e.s.r. difference spectra has been extended to 77 °K. This enables elimination of the main signal due to irradiated silica sample tubes and of about 90% of the hydrogen atom signal from the same source. Under certain conditions, e.g. when the e.s.r. spectrum due to one species can be photochemically bleached, the method permits resolution of two superimposed spectra. This has been demonstrated by measurements which resolve the e.s.r. singlet due to trapped electrons in irradiated tetrahydro-2-methylfuran from the underlying septet. These developments have rendered the e.s.r. difference method very useful for the study of paramagnetic species formed in systems which have been γ-irradiated at 77 °K.

Applications of ESR to Carbonaceous Materials

1982 ◽  
Vol 36 (1) ◽  
pp. 52-57 ◽  
Author(s):  
L. S. Singer ◽  
I. C. Lewis
Keyword(s):  
Free Radicals ◽  
Electron Spin Resonance ◽  
Low Temperature ◽  
Electron Spin ◽  
Paramagnetic Species ◽  
Carbonaceous Materials ◽  
Conduction Electrons ◽  
Spin Resonance ◽  
Higher Temperature ◽  
Low Temperature Pyrolysis

The applications of electron spin resonance (ESR) to carbonaceous materials are reviewed. The stable paramagnetic species observed in the products of low-temperature pyrolysis are odd-alternate neutral free radicals, whereas the unpaired spins of higher temperature carbons and graphites are primarily conduction electrons. The variety of ESR properties and phenomena requires special attention to techniques of measurement and interpretations of results. The relevance to the carbonization process of the free radicals observed by ESR is also discussed.

Paramagnetic resonance and optical absorption of trapped holes and electrons in irradiated KCI: Ag

1963 ◽  
Vol 271 (1345) ◽  
pp. 243-267 ◽  
Keyword(s):  
Electron Spin Resonance ◽  
Low Temperature ◽  
Optical Absorption ◽  
Electron Spin ◽  
Optical Absorption Spectra ◽  
Paramagnetic Resonance ◽  
Spin Resonance ◽  
Impurity Ions ◽  
Temperature Irradiation ◽  
Positive Holes

The electron spin resonance and optical absorption spectra of crystals of KCl containing silver impurity ions were examined after the crystals had been X -irradiated at 77 °K. It is shown that the silver impurity ions act as traps for both electrons and positive holes. A description is given of the annealing behaviour of the crystals after low-temperature irradiation.

Electron spin resonance studies of oriented NO2 and NF2 in inert matrices at low temperatures

1970 ◽  
Vol 48 (5) ◽  
pp. 805-817 ◽  
Author(s):  
C. A. McDowell ◽  
H. Nakajima ◽  
P. Raghunathan
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Low Temperatures ◽  
Hyperfine Splitting ◽  
Preferential Orientation ◽  
Paramagnetic Species ◽  
Host Matrix ◽  
Argon Matrix ◽  
Spin Resonance ◽  
Inert Matrices

Preferentially oriented NO2 and NF2 in inert matrices have been studied in some detail by electron spin resonance methods at 4.2 °K. Methods are discussed which may optimize the degree of preferential orientation of the paramagnetic species in appropriate matrices. The results demonstrate that while neon is the best host matrix for orienting NO2, argon is to be preferred for NF2. The g-values and hyperfine splitting data have been accurately determined and are compared with earlier values. Motional processes are suggested to explain the spectra obtained for NF2 in an argon matrix in the temperature range 4–30 °K.

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