Spin probe mobility in relation to free volume and relaxation dynamics of glass-formers: A series of spin probes in poly(isobutylene)

2009 ◽  
Vol 47 (11) ◽  
pp. 1058-1068 ◽  
Author(s):  
Helena Švajdlenková ◽  
Josef Bartoš
Keyword(s):  
Free Volume ◽  
Spin Probe ◽  
Spin Probes ◽  
Relaxation Dynamics

scholarly journals On the Mutual Relationships between Molecular Probe Mobility and Free Volume and Polymer Dynamics in Organic Glass Formers: cis-1,4-poly(isoprene)

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 294
Author(s):  
Helena Švajdlenková ◽  
Ondrej Šauša ◽  
Sergey V. Adichtchev ◽  
Nikolay V. Surovtsev ◽  
Vladimir N. Novikov ◽  
...  
Keyword(s):  
Free Volume ◽  
Spin Probe ◽  
Hyperfine Coupling Constant ◽  
Organic Glass ◽  
Molecular Probe ◽  
Positron Annihilation Lifetime ◽  
Broadband Dielectric Spectroscopy ◽  
Relaxation Modes ◽  
Reorientation Dynamics ◽  
In Cis

We report on the reorientation dynamics of small spin probe 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) in cis-1,4-poly(isoprene) (cis-1,4-PIP10k) from electron spin resonance (ESR) and the free volume of cis-1,4-PIP10k from positron annihilation lifetime spectroscopy (PALS) in relation to the high-frequency relaxations of cis-1,4-PIP10k using light scattering (LS) as well as to the slow and fast processes from broadband dielectric spectroscopy (BDS) and neutron scattering (NS). The hyperfine coupling constant, 2Azz′(T), and the correlation times, τc(T), of cis-1,4-PIP10k/TEMPO system as a function of temperature exhibit several regions of the distinct spin probe TEMPO dynamics over a wide temperature range from 100 K up to 350 K. The characteristic ESR temperatures of changes in the spin probe dynamics in cis-1,4-PIP10k/TEMPO system are closely related to the characteristic PALS ones reflecting changes in the free volume expansion from PALS measurement. Finally, the time scales of the slow and fast dynamics of TEMPO in cis-1,4-PIP10k are compared with all of the six known slow and fast relaxation modes from BDS, LS and NS techniques with the aim to discuss the controlling factors of the spin probe reorientation mobility in polymer, oligomer and small molecular organic glass-formers.

scholarly journals Molecular dynamic heterogeneity in relation to free volume and relaxation dynamics in organic glass-formers: oligomeric cis-1,4-poly(isoprene)

2017 ◽  
Vol 19 (23) ◽  
pp. 15215-15226 ◽  
Author(s):  
H. Švajdlenková ◽  
S. Arrese-Igor ◽  
Z. Nógellová ◽  
A. Alegría ◽  
J. Bartoš
Keyword(s):  
Molecular Dynamic ◽  
Free Volume ◽  
Molecular Rotation ◽  
Organic Glass ◽  
Relaxation Dynamics ◽  
Dynamic Heterogeneity ◽  
Host Medium ◽  
Rotation Dynamics

Herein, a combined study of the molecular rotation dynamics and free volume in cis-1,4-poly(isoprene) using two external probing techniques via ESR and PALS together with relaxation dynamics of the host medium via BDS is presented.

Spin probe dynamics in relation to free volume in crystalline organics from ESR and PALS: Cyclohexane

2016 ◽  
Vol 643 ◽  
pp. 98-102 ◽  
Author(s):  
H. Švajdlenková ◽  
B. Zgardzinska ◽  
M. Lukešová ◽  
J. Bartoš
Keyword(s):  
Free Volume ◽  
Spin Probe

EPR and ENDOR Investigations of a Cholestane Spin Probe in Liquid Crystals

1987 ◽  
Vol 42 (11) ◽  
pp. 1296-1304 ◽  
Author(s):  
B. Kirste
Keyword(s):  
Liquid Crystals ◽  
Dynamic Behavior ◽  
Spin Probe ◽  
Liquid Crystalline ◽  
Orientational Order ◽  
Spin Probes ◽  
Smectic Phases ◽  
Crystalline Solution

A detailed ENDOR study of anisotropic proton hyperfine shifts in the nitroxide spin probe 3-doxylcholestane (CSL) in liquid-crystalline solution is described. The data are interpreted by means of theoretically calculated proton hyperfine tensors (McConnell-Strathdee-Derbyshire treatment), providing an independent check of the ordering matrix. The orientational order and the dynamic behavior of the nematic and smectic phases of the liquid crystals (40,6), (50,6), and 8CB are investigated by EPR using CSL and phenalenyl as spin probes.

N-14 ENDOR study of micellar solutions of sodium dodecylsulfate using small spin probes

1988 ◽  
Vol 66 (8) ◽  
pp. 1895-1900 ◽  
Author(s):  
Yashige Kotake ◽  
Edward G. Janzen
Keyword(s):  
Intensity Ratio ◽  
Spin Probe ◽  
Double Resonance ◽  
Sodium Dodecylsulfate ◽  
Resonance Spectroscopy ◽  
Spin Probes ◽  
Electron Nuclear Double Resonance ◽  
Spectral Parameters ◽  
Hyperfine Splitting Constant ◽  
Nitroxide Spin Probes

ENDOR (electron nuclear double resonance) spectroscopy has been applied to the study of the state of solubilization of small nitroxide spin probes in micelles produced in sodium dodecylsulfate solution. The intensity ratio of the pair of N-14 ENDOR lines observed by fixing the field on the low-field ESR (electron spin resonance) line was monitored as a measure of the motion of spin probes. Neutral spin probes, when solubilized in micelles, show a discontinuous change of ENDOR spectral parameters such as hyperfine splitting constant and peak intensity ratio. Above the critical micelle concentration, the spectrum features change only gradually as the number of solubilized probes is increased. Spin probes in micelles appear to experience environments that are less polar than those met in aqueous solutions. However, the solubilized state is stable and is insensitive to changes in the concentration of the amphiphile. An anionic spin probe, Fremy's salt, shows no indication of interaction with the micelles. The applicability of the use of ENDOR peak intensities for the study of spin probe motion is discussed.

scholarly journals An EPR spin-probe and spin-trap study of the free radicals produced by plant plasma membranes

2005 ◽  
Vol 70 (2) ◽  
pp. 177-186 ◽  
Author(s):  
Milos Mojovic ◽  
Ivan Spasojevic ◽  
Mirjana Vuletic ◽  
Zeljko Vucinic ◽  
Goran Bacic
Keyword(s):  
Cell Wall ◽  
Free Radicals ◽  
Hydroxyl Radicals ◽  
Spin Probe ◽  
Plasma Membranes ◽  
Spin Trap ◽  
Spectroscopic Techniques ◽  
Spin Probes ◽  
Diphenylene Iodonium ◽  
Kinetics Of

Plant plasma membranes are known to produce superoxide radicals, while the production of hydroxyl radical is thought to occur only in the cell wall. In this work it was demonstrated using combined spin-trap and spin-probe EPR spectroscopic techniques, that plant plasma membranes do produce superoxide and hydroxyl radicals but by kinetically different mechanisms. The results show that superoxide and hydroxyl radicals can be detected by DMPO spin-trap and that the mechanisms and location of their production can be differentiated using the reduction of spin-probes Tempone and 7-DS. It was shown that the mechanism of production of oxygen reactive species is NADH dependent and diphenylene iodonium inhibited. The kinetics of the reduction of Tempone, combined with scavengers or the absence of NADH indicates that hydroxyl radicals are produced by a mechanism independent of that of superoxide production. It was shown that a combination of the spin-probe and spin-trap technique can be used in free radical studies of biological systems, with a number of advantages inherent to them.

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