Defect Identification in Silicon Using Electron Nuclear Double Resonance

1985 ◽  
Vol 46 ◽  
Author(s):  
C.A.J. Ammerlaan ◽  
M. Sprenger ◽  
R. Van Kemp ◽  
D.A. Van Wezep
Keyword(s):  
Electronic Structure ◽  
Point Defects ◽  
Double Resonance ◽  
Paramagnetic Centers ◽  
Electron Nuclear Double Resonance ◽  
Defect Identification ◽  
Vacancy Complex ◽  
Identification And Characterization ◽  
Atomic And Electronic Structure

AbstractThe application of electron nuclear double resonance (ENDOR) for identification and characterization of point defects in silicon is reviewed. Taking the vacancy and the boron-vacancy complex as examples it is discussed how ENDOR can provide information on the atomic and electronic structure of paramagnetic centers.

scholarly journals Selective 13C labelling reveals the electronic structure of flavocoenzyme radicals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Erik Schleicher ◽  
Stephan Rein ◽  
Boris Illarionov ◽  
Ariane Lehmann ◽  
Tarek Al Said ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Blue Light ◽  
Density Functional ◽  
Double Resonance ◽  
Density Functional Theory Calculations ◽  
Microwave Frequency ◽  
Fine Tuning ◽  
Electron Nuclear Double Resonance ◽  
Intermediate Radical ◽  
Wide Range

AbstractFlavocoenzymes are nearly ubiquitous cofactors that are involved in the catalysis and regulation of a wide range of biological processes including some light-induced ones, such as the photolyase-mediated DNA repair, magnetoreception of migratory birds, and the blue-light driven phototropism in plants. One of the factors that enable versatile flavin-coenzyme biochemistry and biophysics is the fine-tuning of the cofactor’s frontier orbital by interactions with the protein environment. Probing the singly-occupied molecular orbital (SOMO) of the intermediate radical state of flavins is therefore a prerequisite for a thorough understanding of the diverse functions of the flavoprotein family. This may be ultimately achieved by unravelling the hyperfine structure of a flavin by electron paramagnetic resonance. In this contribution we present a rigorous approach to obtaining a hyperfine map of the flavin’s chromophoric 7,8-dimethyl isoalloxazine unit at an as yet unprecedented level of resolution and accuracy. We combine powerful high-microwave-frequency/high-magnetic-field electron–nuclear double resonance (ENDOR) with 13C isotopologue editing as well as spectral simulations and density functional theory calculations to measure and analyse 13C hyperfine couplings of the flavin cofactor in DNA photolyase. Our data will provide the basis for electronic structure considerations for a number of flavin radical intermediates occurring in blue-light photoreceptor proteins.

Using Hyperfine Interaction for the Structural Characterization of Amorphous Silicon

1986 ◽  
Vol 69 ◽  
Author(s):  
Martin Stutzmann ◽  
David K. Biegelsen
Keyword(s):  
Hyperfine Interaction ◽  
Amorphous Silicon ◽  
Dipolar Coupling ◽  
Double Resonance ◽  
Nuclear Spins ◽  
Electron Nuclear Double Resonance ◽  
Resonance Frequencies ◽  
Spin Resonance ◽  
Nuclear Spin System

AbstractThe hyperfine interaction between electronic and nuclear spins in hydrogenated amorphous silicon has been observed for the various paramagnetic defects in this material by electron spin resonance (ESR) and electron nuclear double resonance (ENDOR). The large hyperfine interaction between dangling bonds and 29Si as well as between donor electrons and 31p or 75 As nuclei can be resolved in ESR and provides direct information about the structure of the underlying electronic states. The smaller dipolar coupling of all paramagnetic states to more distant nuclei leads to an ENDOR response near the free nuclear resonance frequencies, which can be used to study the coupling of the electronic and nuclear spin system to the lattice phonons and to each other.

Characterization of Atomic Defects and Their Aggregates Using Positron Annihilation Spectroscopy

1984 ◽  
Vol 41 ◽  
Author(s):  
R. W. Siegel ◽  
M. J. Fluss ◽  
L. C. Smedskjaer
Keyword(s):  
Electronic Structure ◽  
Positron Annihilation ◽  
Positron Annihilation Spectroscopy ◽  
Molecular Solids ◽  
Microstructure Development ◽  
Post Irradiation ◽  
Defect Sites ◽  
Atomic And Electronic Structure

AbstractPositrons localize in trapped states at a variety of defect sites in solids, from which they subsequently annihilate with unique observable characteristics. As such, the positron is a valuable probe for the study of these defects. Positron annihilation spectroscopy (PAS) has made significant contributions in recent years to the determination of atomic defect properties in metals and alloys, and in molecular solids as well. It has also been used extensively in the monitoring and characterization of vacancy-like microstructure development, as occurs during post-irradiation annealing. The characterization of defects using PAS is selectively reviewed and some possibilities for using the positron as a localized probe of the atomic and electronic structure of atomic defects and their aggregates are discussed.

Electron nuclear double resonance from paramagnetic centers in ionomers. Titanium(III) in Nafion

1988 ◽  
Vol 21 (2) ◽  
pp. 535-537 ◽  
Author(s):  
Shulamith Schlick ◽  
Lars Sjoqvist ◽  
Anders Lund
Keyword(s):  
Double Resonance ◽  
Paramagnetic Centers ◽  
Electron Nuclear Double Resonance

Electron nuclear double resonance of the F centre in CaF 2

1967 ◽  
Vol 301 (1466) ◽  
pp. 313-326 ◽  
Keyword(s):  
Point Defects ◽  
Alkaline Earth ◽  
Endor Spectrum ◽  
Double Resonance ◽  
Private Communication ◽  
Electron Nuclear Double Resonance ◽  
Colour Centres ◽  
Precise Information ◽  
Hyperfine Constants ◽  
Considerable Body

Although a considerable body of work exists on colour centres in the alkaline earth fluorides, precise information on the structure of intrinsic point defects in these crystals is meagre. Arends (1964) reported an e. p. r. spectrum in additively coloured CaF 2 which he assigned to the F centre. We have carried out endor measurements on additively coloured CaF 2 which confirm that the e. p. r. spectrum described by Arends is indeed due to the F centre. We have measured the hyperfine interaction of the F centre electron with the nuclei of the first four fluorine shells centred on the F centre and we compare our results with preliminary calcula­tions of the hyperfine constants by A. M. Stoneham (private communication). The effects of fluorine-fluorine interaction on the endor spectrum of the first shell fluorines are investigated in detail.

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