Electron nuclear double resonance in solutions. Spin densities in triarylmethyl radicals

1968 ◽  
Vol 90 (16) ◽  
pp. 4225-4231 ◽  
Author(s):  
A. H. Maki ◽  
R. D. Allendoerfer ◽  
J. C. Danner ◽  
R. T. Keys
Keyword(s):  
Double Resonance ◽  
Electron Nuclear Double Resonance ◽  
Spin Densities ◽  
Triarylmethyl Radicals

First-Principles Study of Soliton Hyperfine Interactions in Polyacetylene

1990 ◽  
Vol 209 ◽  
Author(s):  
C. T. White ◽  
F. W. Kutzler ◽  
J. W. Mintmire ◽  
M. R. Cook
Keyword(s):  
Density Functional ◽  
Local Density ◽  
Hyperfine Interactions ◽  
Double Resonance ◽  
Broad Band ◽  
Coupling Constants ◽  
Electron Nuclear Double Resonance ◽  
Neutral Radical ◽  
Fermi Contact ◽  
Spin Densities

ABSTRACTAll-trans-polyacetylene is considered the prototypical broad band gap quasi onedimensional organic semiconductor. Intrinsicsoliton defects have long been known to be important to the understanding of the observed properties of this system at low doping levels. Magnetic resonance techniques provide powerful experimental probes into the nature and environment of these neutral-radical defects. In an earlier work we showed that firstprinciples spin-polarized local density functional (LDF) methods reliably predict proton Fermi-contact coupling constants for planar, neutral, organic π-radicals. We have also used these methods to calculate the Fermi-contact proton coupling constants associated with the soliton defect in polyacetylene.Herein we compare the results of these earlier soliton calculations to results from recent electron-nuclear double-resonance (ENDOR) experiments. Our predicted ratio of the negative to positive spin densities is in good agreement with these ENDORstudies. The negative spin densities arise from spin-polarization effects which are found to cause the soliton level at midgap to be split by several tenths of an eV.

The Microscopic Structure Of Shallow Donors In Silicon Carbide

1996 ◽  
Vol 442 ◽  
Author(s):  
J.-M. Spaeth ◽  
S. Greulich-Weber ◽  
M. März ◽  
E. N. Kalabukhova ◽  
S. N. Lukin
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Dependence ◽  
Double Resonance ◽  
Epr Spectra ◽  
Electron Nuclear Double Resonance ◽  
Paramagnetic Resonance ◽  
Vacancy Pair ◽  
Temperature Spectra ◽  
Electron Paramagnetic

AbstractThe electronic structure of nitrogen donors in 6H-, 4H- and 3C-SiC is investigated by measuring the nitrogen hyperfine (hf) interactions with electron nuclear double resonance (ENDOR) and the temperature dependence of the hf split electron paramagnetic resonance (EPR) spectra. Superhyperfine (shf) interactions with many shells of 13C and 29Si were measured in 6H-SiC. The hf and shf interactions are discussed in the framework of effective mass theory. The temperature dependence is explained with the thermal occupation of the lowest valley-orbit split A1 and E states. It is proposed that the EPR spectra of P donors observed previously in neutron transmuted 6H-SiC at low temperature (<10K) and high temperature (>60K) are all due to substitutional P donors on the two quasi-cubic and hexagonal Si sites, whereby at low temperature the E state is occupied and at high temperature the A1 state. The low temperature spectra are thus thought not to be due to P-vacancy pair defects as proposed previously.

Sign in / Sign up

Export Citation Format

Share Document