An electron spin resonance spectroscopic study of aminocarbonyl nitroxides. Long-range hyperfine splitting of amino substituents and conformational preferences around the C.alpha.-N(O) bond in aminocarbonyl tosylmethyl nitroxides

1977 ◽  
Vol 42 (22) ◽  
pp. 3542-3544 ◽  
Author(s):  
Rense M. Tel ◽  
Jan B. F. N. Engberts
Keyword(s):  
Electron Spin Resonance ◽  
Spectroscopic Study ◽  
Long Range ◽  
Electron Spin ◽  
Hyperfine Splitting ◽  
Conformational Preferences ◽  
Spin Resonance

Hochauflösende EPR-Spektroskopie an organischen Radikalen in flüssigen Kristallen mit nematischer Mesophase

1968 ◽  
Vol 23 (10) ◽  
pp. 1626-1638
Author(s):  
K. Möbius ◽  
H. Haustein ◽  
M. Plato
Keyword(s):  
Liquid Crystal ◽  
Electron Spin Resonance ◽  
Long Range ◽  
Electron Spin ◽  
Hyperfine Splitting ◽  
Interaction Theory ◽  
Axially Symmetric ◽  
G Factor ◽  
Spin Resonance ◽  
Spin Densities

In the nematic and isotropic phases of the liquid crystal p-azoxyanisole (PAA) the neutral radicals perinaphthenyl (PNT), triphenylmethyl (TPM), and pentaphenylcyclopentadienyl (PPCPD) have been studied by electron spin resonance techniques. A method is discussed for measuring the degree of ordering of the radicals by means of the observed g factors in the different phases. For PNT and TPM the components of the axially symmetric g tensor are determined and compared with the values predicted by STONE’S g factor theory. The shift of the hyperfine splitting constants (C13 and H1) of PNT and TPM agree rather well with the theoretical shifts calculated by the dipol-dipol interaction theory of Mc CONNELL and STRATHDEE. For TPM, however, the agreement is only satisfactory when all the long range contributions are considered. For PNT and TPM also the signs of the spin densities could be determined. PPCPD shows drastically that the validity of both g factor theory and hfs theory in nematic mesophases breaks down for unplanar molecules with large twist angles.

Dichromated poly(vinyl alchohol)-xanthene dye systems: holographic characterization and electron spin resonance spectroscopic study

1994 ◽  
Author(s):  
Gurusamy Manivannan ◽  
Rupak Changkakoti ◽  
Roger A. Lessard ◽  
Gilles Mailhot ◽  
Michel Bolte
Keyword(s):  
Electron Spin Resonance ◽  
Spectroscopic Study ◽  
Electron Spin ◽  
Spin Resonance

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.

An ESR and calorimetric study of iron oolitic samples from the Northampton ironstone

Clay Minerals ◽  
1990 ◽  
Vol 25 (3) ◽  
pp. 303-311 ◽  
Author(s):  
A. U. Gehring ◽  
R. Karthein
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Hyperfine Splitting ◽  
Esr Spectroscopy ◽  
Thermal Conversion ◽  
Esr Spectra ◽  
Calorimetric Study ◽  
Calorimetric Methods ◽  
Mineral Phases ◽  
Spin Resonance

AbstractElectron spin resonance (ESR) spectroscopy and calorimetric methods were used to characterize conversion processes in multimineral samples from the Northampton ironstone (NIS) at temperatures between 25°C and 800°C. The beginning of the thermal conversion processes can be determined by the formation of asymmetric ESR spectra with g ≈ 2 at 250°C. The breakdown of the berthierine structure between 250°C and 520°C is indicated by the disappearance of the hyperfine splitting in the Mn2+ spectrum and the formation of magnetite. The decomposition of siderite and calcite was found by calorimetric methods at 580°C and 700°C, respectively. The hematite formation between 550°C and 800°C is explained by the decomposition of siderite but also by the oxidation of previously formed magnetite. The occurrence of hematite as the dominant ferric oxide at 800°C signifies the end of the conversion process of the major mineral phases in the NIS samples.

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