scholarly journals Exohedral Functionalization of Fullerene by Substituents Controlling of Molecular Organization for Spontaneous C60 Dimerization in Liquid Crystal Solutions and in a Bulk Controlled by a Potential

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2816
Author(s):  
Malgorzata Czichy ◽  
Alessia Colombo ◽  
Pawel Wagner ◽  
Patryk Janasik ◽  
Claudia Dragonetti ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Room Temperature ◽  
Reduction Potential ◽  
Van Der Waals Interactions ◽  
Molecular Organization ◽  
Structural Elements ◽  
Paramagnetic Resonance ◽  
Coulombic Repulsion ◽  
Covalently Bonded ◽  
Electron Paramagnetic

A study was carried out on the possibility of orderly and spontaneous dimerization at room temperature of C60 cages in fullerene liquid crystal fullerene dyads (R-C60). For this purpose, dyads with a structural elements feature supporting π-stacking and Van der Waals interactions were tested, due to the presence of terthiophene donors linked through an α-position or dodecyloxy chains. In addition, this possibility was also tested and compared to dyads with shorter substituents and the pristine C60. Research has shown that only in dyads with the features of liquid crystals, π-dimerization of C60 units occurs, which was verified by electrochemical and spectroelectrochemical (ESR) measurements. Cyclic voltammetry and differential voltammetry studies reveal π-dimerization in liquid crystal dyad solution even without the possibility of previous polymerization (cathodic or anodic) under conditions in the absence of irradiation and without the availability of reaction initiators, and even with the use of preliminary homogenization. These dyads undergo six sequential, one-electron reductions of π-dimer (R-C60···C60-R), where two electrons are added successively to each of the two fullerene cages and first form two radical anion system (R-C60)•−(R-C60)•− without pairing with the characteristics of two doublets. Similarly, the second reductions of π-dimer occur at potentials that are close to the reduction potential for the conversion to a system of two triplet dianions (R-C60)2−(R-C60)2−. Electron paramagnetic resonance spectra indicate a significant interaction between C60 cages. Interestingly, the strength of intermolecular bonds is so significant that it can overcome Coulombic repulsion, even with such highly charged particles as dianions and trianions. Such behavior has been revealed and studied so far only in covalently bonded C60 dimers.

Temperature Dependent Line-Shape of the Silicon Dangling Bond EPR-Resonance in Polycrystalline Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
N. H. Nickel ◽  
E. A. Schiff
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Polycrystalline Silicon ◽  
Room Temperature ◽  
Dangling Bond ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Temperature Electron ◽  
Motional Narrowing ◽  
G Value ◽  
Electron Paramagnetic

AbstractThe temperature dependence of the silicon dangling-bond resonance in polycrystalline (poly-Si) and amorphous silicon (a-Si:H) was measured. At room temperature, electron paramagnetic resonance (EPR) measurements reveal an isotropie g-value of 2.0055 and a line width of 6.5 and 6.1 G for Si dangling-bonds in a-Si:H and poly-Si, respectively. In both materials spin density and g-value are independent of temperature. While in a-Si:H the width of the resonance did not change with temperature, poly-Si exhibits a remarkable T dependence of ΔHpp. In unpassivated poly-Si a pronounced decrease of ΔHpp is observed for temperatures above 300 K. At 384 K ΔHpp reaches a minimum of 5.1 G, then increases to 6.1 G at 460 K, and eventually decreases to 4.6 G at 530 K. In hydrogenated poly-Si ΔHpp decreases monotonically above 425 K. The decrease of ΔHpp is attributed to electron hopping causing motional narrowing. An average hopping distance of 15 and 17.5 Å was estimated for unhydrogenated and H passivated poly-Si, respectively.

scholarly journals EPR Spectra of Sintered Cd1−xCrxTe Powdered Crystals with Various Cr Content

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3449
Author(s):  
Ireneusz Stefaniuk ◽  
Werner Obermayr ◽  
Volodymyr D. Popovych ◽  
Bogumił Cieniek ◽  
Iwona Rogalska
Keyword(s):  
Curie Temperature ◽  
Room Temperature ◽  
Integral Intensity ◽  
Resonance Field ◽  
Epr Spectra ◽  
Paramagnetic Resonance ◽  
Simple Method ◽  
Paramagnetic Curie Temperature ◽  
Cr Content ◽  
Electron Paramagnetic

In this paper, we show a simple method of producing ferromagnetic materials with a Curie temperature above room temperature. The electron paramagnetic resonance (EPR) spectra of Cd1−xCrxTe (0.002 < x < 0.08) were measured with a dependence on temperature (82 K < T < 381 K). Obtained EPR lines were fitted to a Lorentz-shaped curve. The temperature dependencies of the parameters of the EPR lines, such as the peak-to-peak linewidth (Hpp), the intensity (A), as well as the resonance field (Hr), were studied. Ferromagnetism was noticed in samples at high temperatures (near room temperature). For a sample with a nominal concentration of chrome of x = 0.05, a very strong intrinsic magnetic field is observed. The value of the effective gyromagnetic factor for this sample is ge = 30 at T = 240 K. An increase of chrome concentration above x = 0.05 reduces the ferromagnetic properties considerably. Analysis of the temperature dependencies of the integral intensity of EPR spectra was carried out using the Curie–Weiss law and the paramagnetic Curie temperature was obtained.

Room Temperature Electron Paramagnetic Resonance (EPR) Signal Storage

1969 ◽  
Author(s):  
D.A. Bozanic ◽  
D.C. Buck ◽  
F.H. Harris ◽  
R.E. Huber ◽  
D. Mergerian ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Room Temperature ◽  
Paramagnetic Resonance ◽  
Temperature Electron ◽  
Epr Signal ◽  
Electron Paramagnetic

Paramagnetic Defects in Benitoite

1991 ◽  
Vol 46 (7) ◽  
pp. 579-582 ◽  
Author(s):  
A. B. Vassilikou-Dova ◽  
K. Eftaxias
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Hyperfine Interaction ◽  
Relative Intensity ◽  
Room Temperature ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic ◽  
Magnetic Defects

Abstract In clear, blue, transparent bipyramidal crystals of the rare mineral benitoite, BaTiSi3O9, para­ magnetic defects have been investigated by electron paramagnetic resonance at room temperature and 9.43 GHz. They are attributed to Sn3+ and Fe3+ . A pair of satellites recorded for a wide angular rage around B0 || c (~40°) and a relative intensity of ~ 13% to the central signal is most likely due to hyperfine interaction with 117Sn and 119Sn isotopes. Attempts to bleach the colour of the crystal were unsuccessful.

Transient electron paramagnetic resonance of the triplet state of P700 in photosystem I: Evidence for triplet delocalization at room temperature

Biochemistry ◽  
1993 ◽  
Vol 32 (18) ◽  
pp. 4842-4847 ◽  
Author(s):  
Ina Sieckmann ◽  
Klaus Brettel ◽  
Christian Bock ◽  
Arthur van der Est ◽  
Dietmar Stehlik
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Triplet State ◽  
Photosystem I ◽  
Room Temperature ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

Luminescence and EPR Study of Lithium-Diffused ZnO Crystals

2002 ◽  
Vol 744 ◽  
Author(s):  
N. Y. Garces ◽  
Lijun Wang ◽  
M. M. Chirila ◽  
L. E. Halliburton ◽  
N. C. Giles
Keyword(s):  
Room Temperature ◽  
Deep Level ◽  
Chemical Vapor ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Paramagnetic Resonance ◽  
Lithium Diffusion ◽  
Before And After ◽  
Electron Paramagnetic ◽  
Transport Method

ABSTRACTZinc oxide (ZnO) crystals grown by the seeded chemical vapor transport method have been studied using photoluminescence (PL), thermoluminescence (TL), and electron paramagnetic resonance (EPR) techniques. Lithium acceptors were diffused into the crystals during anneals in LiF powder at temperatures in the 750 to 850°C range. After a lithium diffusion, EPR was used to monitor neutral lithium acceptors and neutral shallow donors, as well as Ni3+, Fe3+, and Cu2+ impurities unintentionally present. Excitonic and deep-level PL emissions were also monitored before and after these diffusions. Two broad overlapping TL emission bands were observed at 117 and 145 K when a Li-diffused crystal was illuminated at 77 K with 325-nm light and then rapidly warmed to room temperature. The two TL bands have the same spectral dependence (the peak in wavelength is 540 nm when the intensity of the light reaches a maximum). These “glow” peaks occur when electrons are thermally released from Ni2+ and Fe2+ ions and recombine with holes at neutral lithium acceptors.

EPR of Gamma-irradiated L-Glutamine Hydrochloride and N-Carbamoyl-L-glutamic Acid

2005 ◽  
Vol 60 (7) ◽  
pp. 549-553 ◽  
Author(s):  
Şemsettin Osmanoğlua ◽  
Murat Aydın ◽  
M. Halim Başkana
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Glutamic Acid ◽  
Radiation Damage ◽  
Single Crystals ◽  
Room Temperature ◽  
Paramagnetic Resonance ◽  
Temperature Radiation ◽  
Gamma Irradiated ◽  
Electron Paramagnetic

The electron paramagnetic resonance spectra of γ -irradiated L-glutamine hydrochloride and N-carbamoyl- L-glutamic acid single crystals have been investigated at room temperature. Radiation damage centres are attributed to ĊH, ṄH2 and CH2Ċ(NH2)COOH radicals.

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