EPR of a fullerene-molecule-derived paramagnetic center as a mesoscopic conducting object

Stankowski, J.; Piekara-Sady, L.; Kempiński, W.

doi:10.1007/bf03162398

Cited by 9 publications

(5 citation statements)

References 19 publications

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“…The g-tensor components of the photo-generated electron localized at the fullerene cage in all blends with P3HT were very similar to those in pure fullerene derivatives (data in Supplementary Materials ), and all of them were well below the free electron g-factor (g = 2.0023). Such negative deviation most probably results from the spin–orbit coupling with the unoccupied π-orbital, while positive deviation has been considered to arise from the spin–orbit coupling with the occupied orbitals [ 37 , 38 ]. The LESR signals of electrons at the fullerene cage showed only slight differences between the various molecule blends, indicating a rather weak influence of the different fullerene functional groups.…”

Section: Resultsmentioning

confidence: 99%

Optical Properties and Light-Induced Charge Transfer in Selected Aromatic C60 Fullerene Derivatives and in Their Bulk Heterojunctions with Poly(3-Hexylthiophene)

et al. 2022

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Fullerene derivatives offer great scope for modification of the basic molecule, often called a buckyball. In recent years, they have been the subject of numerous studies, in particular in terms of their applications, including in solar cells. Here, the properties of four recently synthesized fullerene C60 derivatives were examined regarding their optical properties and the efficiency of the charge transfer process, both in fullerene derivatives themselves and in their heterojunctions with poly (3-hexylthiophene). Optical absorption, electron spin resonance (ESR), and time-resolved photoluminescence (TRPL) techniques were applied to study the synthesized molecules. It was shown that the absorption processes in fullerene derivatives are dominated by absorption of the fullerene cage and do not significantly depend on the type of the derivative. It was also found by ESR and TRPL studies that asymmetrical, dipole-like derivatives exhibit stronger light-induced charge transfer properties than their symmetrical counterparts. The observed inhomogeneous broadening of the ESR lines indicated a large disorder of all polymer–fullerene derivative blends. The density functional theory was applied to explain the results of the optical absorption experiments.

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Section: Resultsmentioning

confidence: 99%

Optical Properties and Light-Induced Charge Transfer in Selected Aromatic C60 Fullerene Derivatives and in Their Bulk Heterojunctions with Poly(3-Hexylthiophene)

et al. 2022

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“…Observed changes of line width, together with a small g-shift from g e -spectroscopic splitting factor of free electron (g − g e = ∆g = 6 × 10 −4 ; mean value) for line (2) of C 6 H 5 NO 2 -filled ACFs, enabled us to estimate the size of graphite nanoparticles (approximately 1.34 nm) in which distance between graphene plates could be modified by guests molecules [11]. Such an approach was also proposed for ultra dispersed diamond (UDD) [8] and fullerenes [12]. Line width and g-factor of the component (3) of observed EPR spectrum strongly depend on temperature -it can be explained as a surface effect of ACFs.…”

Section: Resultsmentioning

confidence: 99%

Size Modification of Nanographite System of Activated Carbon Fibers Studied by EPR

Kempiński

Śliwińska-Bartkowiak

2005

Acta Phys. Pol. A

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We report results of EPR measurements of activated carbon fibers. Experiments made for pristine activated carbon fibers and activated carbon fibers with adsorbed molecules (CCl 4 , C 6 H 5 NO 2 , and H 2 O) confirmed the localized character of paramagnetic centers observed in the system. Pristine activated carbon fibers are characterized by single Lorentzian line. Broader component of EPR signal appears when guest molecules are adsorbed in nanopores. The strongest localization is observed for water-filled activated carbon fibers nanopores (with hydrophobic pore walls) where changes in distance between nanographite particles were monitored by the g-shift to higher values. This process is related to stronger spin-orbit interaction of electrons trapped at nanographite particles compressed by guest molecules.

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“…The four‐component spectrum in Shungite IV belongs just to such complexes. Their g ‐factors are close to 2.0000 17, 18. Such complexes exist independently from the conducting carbon system and the deep levels of the band gap present their energy states.…”

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confidence: 78%

Paramagnetic resonance of Shungite – a natural nano‐structured carbonaceous material

Yablokov

Augustyniak-Jabłokow

Kempiński

et al. 2006

Physica Status Solidi (b)

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Shungite is a new variety of natural carbonaceous rocks with carbon content (98-20%) depending on the particular deposit (Chebolaksha, Maksovo, Nigozero, Shunga, Zazhogino) in Karelia (Russia) [1]. The occurrence of the natural С 60 and С 70 fullerenes was proved first for Shungite [2]. Fullerene type formations from single C 60(70) to globules of ~10 nm in size were reported in this material. Disordered multilayer carbon globules of ~10 nm make separate elements supplemented in Shungite with the uniformly distributed SiO 2 , metal oxides, mica and other admixtures [3]. The supramolecular structure of the totality of the globules changes in the samples of different deposits, however, the main features of the carbon units remain unchanged [3]. The interest in Shungite stems from the possibility of its use in industry and medicine [1].The studies of the physical properties of Shungite are at the beginning stage [4,5], however, the specific features of this material have been already recognised. The first measurements of the magnetic susceptibility yield an intriguing result [6]: in Sh-I (98% of carbon) the change in χ d was similar to that corresponding to the appearance of superconductivity at 95 K in the fullerenes doped with Сu 2+ [7]. In this article we report the first EPR study of Shungite samples (Sh-III, 55-25% carbon and Sh-IV, 25-5%). The observed spectra definitely confirm the presence of electrical conductivity characteristic of metals, however, the properties of Shungite differ from both those of metals and those of graphite (and fullerenes). We have studied the Shungite samples from two deposits (Sh-III and Sh-IV). EPR measurements were carried on an X-band RADIO-PAN spectrometer in the 300-4.2 K temperature range.For the Sh-III sample of ∼3 × 1 × 0.5 mm 3 size a relatively week signal of the Dyson shape [8] was observed (Fig. 1a). It was characterized by the asymmetry parameter a/b varying from 2.40 to 2.25 depending on the angle between the constant magnetic field direction and the sample surface. At the same time, changes in the linewidth were insignificant, and ∆В eff was equal 1.99 ± 0.04 mT. After the sample grinding, the signal intensity increased more than ten times and became absolutely symmetric (∆В = 1.82 ± 0.05 mT; g-factor = 2.0019 ± 0.0002; Fig. 1b). Measurements of the fine-ground sample degassed in vacuum 2 × 10 -6 mm Hg on heating up to 200 °С, showed that the molecular oxygen usually adsorbed on the surface crystallites did not affect the EPR signal, as it was observed sometimes in a variety of graphites and carbon blacks [9].The temperature dependence of the EPR signal of Sh-III was studied both for powder and for the bulk sample. (Na + ) have been found in Sh-IV. Analysis of the EPR spectra has been made taking into consideration the properties of the conductive materials such as metals and graphite.

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EPR of a fullerene-molecule-derived paramagnetic center as a mesoscopic conducting object

Cited by 9 publications

References 19 publications

Optical Properties and Light-Induced Charge Transfer in Selected Aromatic C60 Fullerene Derivatives and in Their Bulk Heterojunctions with Poly(3-Hexylthiophene)

Optical Properties and Light-Induced Charge Transfer in Selected Aromatic C60 Fullerene Derivatives and in Their Bulk Heterojunctions with Poly(3-Hexylthiophene)

Size Modification of Nanographite System of Activated Carbon Fibers Studied by EPR

Paramagnetic resonance of Shungite – a natural nano‐structured carbonaceous material

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