Electron spin relaxation and quantum localization in carbon nanoparticle: Electron spin echo studies

2008 ◽  
Vol 77 (1) ◽  
Author(s):  
Stefan Lijewski ◽  
Magdalena Wencka ◽  
Stanislaw K. Hoffmann ◽  
Mateusz Kempinski ◽  
Wojciech Kempinski ◽  
...  
Keyword(s):  
Spin Relaxation ◽  
Electron Spin ◽  
Spin Echo ◽  
Electron Spin Echo ◽  
Carbon Nanoparticle ◽  
Electron Spin Relaxation ◽  
Quantum Localization

scholarly journals Triarylmethyl Radical: EPR Signal to Noise at Frequencies between 250 MHz and 1.5 GHz and Dependence of Relaxation on Radical and Salt Concentration and on Frequency

2017 ◽  
Vol 231 (4) ◽  
Author(s):  
Yilin Shi ◽  
Richard W. Quine ◽  
George A. Rinard ◽  
Laura Buchanan ◽  
Sandra S. Eaton ◽  
...  
Keyword(s):  
Spin Relaxation ◽  
Electron Spin ◽  
Salt Concentration ◽  
Spin Echo ◽  
Electron Spin Echo ◽  
Relaxation Rates ◽  
Optimum Frequency ◽  
Paramagnetic Resonance ◽  
Electron Spin Relaxation

AbstractIn vivo oximetry by pulsed electron paramagnetic resonance is based on measurements of changes in electron spin relaxation rates of probe molecules, such as the triarylmethyl radicals. A series of experiments was performed at frequencies between 250 MHz and 1.5 GHz to assist in the selection of an optimum frequency for oximetry. Electron spin relaxation rates for the triarylmethyl radical OX063 as a function of radical concentration, salt concentration, and resonance frequency were measured by electron spin echo 2-pulse decay and 3-pulse inversion recovery in the frequency range of 250 MHz–1.5 GHz. At constant OX063 concentration, 1/T

Free radicals and their electron spin relaxation in cellobiose. X-band and W-band ESR and electron spin echo studies

Cellulose ◽  
2006 ◽  
Vol 14 (3) ◽  
pp. 183-194 ◽  
Author(s):  
Magdalena Wencka ◽  
Kinga Wichlacz ◽  
Henryk Kasprzyk ◽  
Stefan Lijewski ◽  
Stanislaw K. Hoffmann
Keyword(s):  
Free Radicals ◽  
Spin Relaxation ◽  
Electron Spin ◽  
Spin Echo ◽  
Electron Spin Echo ◽  
Electron Spin Relaxation ◽  
W Band ◽  
X Band

scholarly journals Electron Spin Relaxation of Photoexcited Porphyrin in Water—Glycerol Glass

Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2677
Author(s):  
Natalya Sannikova ◽  
Ivan Timofeev ◽  
Elena Bagryanskaya ◽  
Michael Bowman ◽  
Matvey Fedin ◽  
...  
Keyword(s):  
Spin Relaxation ◽  
Electron Spin ◽  
Solvent Accessibility ◽  
Spin Echo ◽  
Relaxation Times ◽  
Electron Spin Echo ◽  
Water Soluble ◽  
Paramagnetic Resonance ◽  
Electron Spin Relaxation ◽  
Water Glycerol

Recently, the photoexcited triplet state of porphyrin was proposed as a promising spin-label for pulsed dipolar electron paramagnetic resonance (EPR). Herein, we report the factors that determine the electron spin echo dephasing of the photoexcited porphyrin in a water–glycerol matrix. The electron spin relaxation of a water-soluble porphyrin was measured by Q-band EPR, and the temperature dependence and the effect of solvent deuteration on the relaxation times were studied. The phase memory relaxation rate (1/Tm) is noticeably affected by solvent nuclei and is substantially faster in protonated solvents than in deuterated solvents. The Tm is as large as 13–17 μs in deuterated solvent, potentially expanding the range of distances available for measurement by dipole spectroscopy with photoexcited porphyrin. The 1/Tm depends linearly on the degree of solvent deuteration and can be used to probe the environment of a porphyrin in or near a biopolymer, including the solvent accessibility of porphyrins used in photodynamic therapy. We characterized the noncovalent binding of porphyrin to human serum albumin (HSA) from 1/Tm and electron spin echo envelope modulation (ESEEM) and found that porphyrin is quite exposed to solvent on the surface of HSA. The 1/Tm and ESEEM are equally effective and provide complementary methods to determine the solvent accessibility of a porphyrin bound to protein or to determine the location of the porphyrin.

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