Characterization of Cu(II) Bipyridine Complexes in Halogen Atom Transfer Reactions by Electron Spin Resonance

2003 ◽  
Vol 36 (22) ◽  
pp. 8291-8296 ◽  
Author(s):  
Bernhard Knuehl ◽  
Tomislav Pintauer ◽  
Atsushi Kajiwara ◽  
Hanns Fischer ◽  
Krzysztof Matyjaszewski
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Halogen Atom ◽  
Transfer Reactions ◽  
Atom Transfer ◽  
Spin Resonance ◽  
Atom Transfer Reactions

Characterizations of radicals formed in radical polymerizations and transfer reactions by electron spin resonance spectroscopy

2018 ◽  
Vol 90 (8) ◽  
pp. 1237-1254 ◽  
Author(s):  
Atsushi Kajiwara
Keyword(s):  
Electron Spin Resonance ◽  
Radical Polymerization ◽  
Electron Spin ◽  
Transfer Reactions ◽  
Resonance Spectroscopy ◽  
Spin Resonance ◽  
Radical Transfer ◽  
Radical Polymerizations ◽  
Chain Lengths

Abstract Electron spin resonance (ESR, aka electron paramagnetic resonance, EPR) investigations have been conducted on radicals formed during radical polymerizations and provide a detailed characterization of the active radical species. Active propagating radicals can be observed during actual radical polymerizations by ESR/EPR. The chain lengths of the observed radicals were estimated by a combination of atom transfer radical polymerization (ATRP) and ESR/EPR. The structures of the chain end radicals were determined by analysis of the ESR/EPR spectra. An increase in the dihedral angles between terminal p-orbital of radical and Cβ–H bonds was observed with increasing chain lengths of methacrylate polymers. Radical transfer reactions were observed during radical polymerization of acrylates. A combination of ATRP and ESR/EPR clarified a 1,5-hydrogen shift mechanism of the radical transfer reactions using model adamantyl acrylate radicals. Penultimate unit effects were also observed. Time-resolved ESR/EPR (TR ESR) spectroscopy clarified the initiation processes of an alternating copolymerization of styrene with maleic anhydride and the copolymerization of styrene with 1,3-butadiene. Several unsolved problems in conventional radical polymerization processes have been clarified using combinations of ATRP with ESR/EPR and TR ESR. Characterization of the radicals in radical polymerizations using various ESR techniques would definitely provide interesting and useful information on conventional radical polymerizations.

Electron Spin Resonance Characterization of Defects at Interfaces in Stacks of Ultrathin High-κ Dielectric Layers on Silicon

2003 ◽  
Vol 786 ◽  
Author(s):  
A. L. Stesmans ◽  
V.V. Afanas'ev
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Dielectric Layers ◽  
Growth Standard ◽  
Spin Resonance ◽  
Dielectric Interfaces ◽  
Standard Quality

ABSTRACTElectron spin resonance (ESR) analysis of (100)Si/SiOx/ZrO2, (100)Si/Al2O3 and Si/HfO2 structures with nm-thin dielectric layers deposited by different chemical vapor deposition procedures reveals, after hydrogen detachment, the presence of the trivalent Si dangling-bond-type centers Pb0, Pb1 as prominent defects in all entities. This Pb0, Pb1 fingerprint, generally unique for the thermal (100)Si/SiO2 interface, indicates that the as-deposited (100)Si/metal oxides interface is basically Si/SiO2-like. Though sensitive to the deposition process, the Pb0 density is found to be substantially larger than in standard (100)Si/SiO2. As probed by the Pb- type center properties, the Si/dielectric interfaces of all structures are under enhanced (unrelaxed) stress, typical for low temperature Si/SiO2 growth. Standard quality thermal Si/SiO2 properties in terms of Pb signature may be approached by appropriate annealing (≥ 650°C) in vacuum in the case of (100)Si/SiOx/ZrO2. Yet, O2 ambient appears required for Si/Al2O3 and Si/HfO2. It appears that Si/high-κ metal oxide structures with device grade quality interfaces can be realized with sub-nm thin SiOx interlayers. The density of fast interface states closely matches the Pb0 density variations, suggesting the center as the dominant fast interface trap. They may be efficiently passivated in H2 at 400 °C.

scholarly journals Characterization of manganese in coal by electron spin resonance.

1985 ◽  
Vol 34 (5) ◽  
pp. 243-247 ◽  
Author(s):  
Junichi SHIDA ◽  
Mamoru ITOH ◽  
Tateaki OGATA ◽  
Hitoshi KAMADA
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Spin Resonance

scholarly journals Two-dimensional pulsed electron spin resonance characterization of 15 N-labeled archaeal Rieske-type ferredoxin

FEBS Letters ◽  
2009 ◽  
Vol 583 (21) ◽  
pp. 3467-3472 ◽  
Author(s):  
Toshio Iwasaki ◽  
Rimma I. Samoilova ◽  
Asako Kounosu ◽  
Sergei A. Dikanov
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Two Dimensional ◽  
Spin Resonance
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