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Leonid V Kulik - One of the best experts on this subject based on the ideXlab platform.
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higher triplet state of Fullerene C70 revealed by electron spin relaxation
Journal of Chemical Physics, 2015Co-Authors: Mikhail N Uvarov, Jan Behrends, Leonid V KulikAbstract:Spin-lattice relaxation times T1 of photoexcited triplets (3)C70 in glassy decalin were obtained from electron spin echo inversion recovery dependences. In the range 30-100 K, the temperature dependence of T1 was fitted by the Arrhenius law with an activation energy of 172 cm(-1). This indicates that the dominant relaxation process of (3)C70 is described by an Orbach-Aminov mechanism involving the higher triplet state t2 which lies 172 cm(-1) above the lowest triplet state t1. Chemical modification of C70 Fullerene not only decreases the intrinsic triplet lifetime by about ten times but also increases T1 by several orders of magnitude. The reason for this is the presence of a low-lying excited triplet state in (3)C70 and its absence in triplet C70 derivatives. The presence of the higher triplet state in C70 is in good agreement with the previous results from phosphorescence spectroscopy.
Jae-hong Kim - One of the best experts on this subject based on the ideXlab platform.
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Differential photoactivity of aqueous [C60] and [C70] Fullerene aggregates.
Environmental science & technology, 2015Co-Authors: Kyle J. Moor, Samuel D. Snow, Jae-hong KimAbstract:Many past studies have focused on the aqueous photochemical properties of colloidal suspensions of C60 and various [C60] Fullerene derivatives, yet few have investigated the photochemistry of other larger cage Fullerene species (e.g., C70, C74, C84, etc.) in water. This is a critical knowledge gap because these larger Fullerenes may exhibit different properties compared to C60, including increased visible light absorption, altered energy level structures, and variable cage geometries, which may greatly affect aggregate properties and resulting aqueous photoactivity. Herein, we take the first steps toward a detailed investigation of the aqueous photochemistry of larger cage Fullerene species, by focusing on [C70] Fullerene. We find that aqueous suspensions of C60 and C70, nC60 and nC70, respectively, exhibit many similar physicochemical properties, yet nC70 appears to be significantly more photoactive than nC60. Studies are conducted to elucidate the mechanism behind nC70’s superior 1O2 generation, includi...
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Improving the Visible Light Photoactivity of Supported Fullerene Photocatalysts through the Use of [C70] Fullerene
Environmental science & technology, 2015Co-Authors: Kyle J. Moor, Dhyan C. Valle, Jae-hong KimAbstract:We herein present the first instance of employing [C70] Fullerene for photocatalytic 1O2 production in water, through covalent immobilization onto a mesoporous silica support via nucelophilic amine addition directly to Fullerene’s cage. This attachment approach prevents the aggregation of individual Fullerene molecules in water, thus allowing Fullerene to retain its photoactivity, yet is much less complex than other techniques commonly pursued to create such supported-Fullerene materials, which typically rely on water-soluble Fullerene derivatives and elaborate immobilization methods. The solid-supported C70 material exhibits significantly improved aqueous visible-light photoactivity compared to previous C60- and C60-derivative-based supported Fullerene materials. Further, this material rapidly inactivates MS2 bacteriophage under sunlight illumination, oxidizes various organic contaminants, and does not appear to be significantly fouled by natural organic matter (NOM), highlighting the potential of these ...
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C70 Fullerene sensitized triplet triplet annihilation upconversion
Chemical Communications, 2013Co-Authors: Kyle J. Moor, Samuel D. Snow, Jae-hong Kim, Jaehyuk KimAbstract:We herein report the first instance of using pristine C70 as a heavy-atom free organic sensitizer for efficient triplet–triplet annihilation upconversion (UC) for both green-to-blue and red-to-green UC using 9,10-bis(phenylethynyl)anthracene and perylene as acceptors, respectively. C70 achieved quantum yields of 8% and 0.8% for green-to-blue and red-to-green UC, 25 to 35 times higher than C60, and showed improved stability under continuous laser irradiation compared to the benchmark platinum(II)-octaethylporphyrin.
Arthur L. Lafleur - One of the best experts on this subject based on the ideXlab platform.
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c60 and C70 Fullerene isomers generated in flames detection and verification by liquid chromatography mass spectrometry analyses
Rapid Communications in Mass Spectrometry, 1992Co-Authors: Joseph F. Anacleto, Hélène Perreault, Robert K. Boyd, Stephen Pleasance, Michael A. Quilliam, Jack B. Howard, Yakov Makarvovsky, Greig P Sim, Arthur L. LafleurAbstract:Fullerenes C60 and C70, generated by combustion, have been shown previously to be produced in controlled laminar flames accompanied by other compounds having Fullerene-like characteristics. Analysis of these additional compounds by high-performance liquid chromatography, coupled on-line with mass spectrometry has identified them as isomers of the C60 and C70 Fullerenes. The newly observed isomers have characteristic UV spectra and are thermally unstable, undergoing conversion to the more stable Fullerenes with a half-life of about 1 h in boiling toluene (111 degrees C). Isomers of C60 and C70 Fullerenes previously have been studied theoretically, but not observed experimentally. The flame-generated material also contains C60O and C70O compounds, as well as C76 and higher carbon clusters.
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C60 and C70 Fullerene isomers generated in flames. Detection and verification by liquid chromatography/mass spectrometry analyses
Rapid communications in mass spectrometry : RCM, 1992Co-Authors: Joseph F. Anacleto, Hélène Perreault, Robert K. Boyd, Stephen Pleasance, Michael A. Quilliam, P. Greig Sim, Jack B. Howard, Yakov Makarvovsky, Arthur L. LafleurAbstract:Fullerenes C60 and C70, generated by combustion, have been shown previously to be produced in controlled laminar flames accompanied by other compounds having Fullerene-like characteristics. Analysis of these additional compounds by high-performance liquid chromatography, coupled on-line with mass spectrometry has identified them as isomers of the C60 and C70 Fullerenes. The newly observed isomers have characteristic UV spectra and are thermally unstable, undergoing conversion to the more stable Fullerenes with a half-life of about 1 h in boiling toluene (111 degrees C). Isomers of C60 and C70 Fullerenes previously have been studied theoretically, but not observed experimentally. The flame-generated material also contains C60O and C70O compounds, as well as C76 and higher carbon clusters.
Joseph F. Anacleto - One of the best experts on this subject based on the ideXlab platform.
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c60 and C70 Fullerene isomers generated in flames detection and verification by liquid chromatography mass spectrometry analyses
Rapid Communications in Mass Spectrometry, 1992Co-Authors: Joseph F. Anacleto, Hélène Perreault, Robert K. Boyd, Stephen Pleasance, Michael A. Quilliam, Jack B. Howard, Yakov Makarvovsky, Greig P Sim, Arthur L. LafleurAbstract:Fullerenes C60 and C70, generated by combustion, have been shown previously to be produced in controlled laminar flames accompanied by other compounds having Fullerene-like characteristics. Analysis of these additional compounds by high-performance liquid chromatography, coupled on-line with mass spectrometry has identified them as isomers of the C60 and C70 Fullerenes. The newly observed isomers have characteristic UV spectra and are thermally unstable, undergoing conversion to the more stable Fullerenes with a half-life of about 1 h in boiling toluene (111 degrees C). Isomers of C60 and C70 Fullerenes previously have been studied theoretically, but not observed experimentally. The flame-generated material also contains C60O and C70O compounds, as well as C76 and higher carbon clusters.
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C60 and C70 Fullerene isomers generated in flames. Detection and verification by liquid chromatography/mass spectrometry analyses
Rapid communications in mass spectrometry : RCM, 1992Co-Authors: Joseph F. Anacleto, Hélène Perreault, Robert K. Boyd, Stephen Pleasance, Michael A. Quilliam, P. Greig Sim, Jack B. Howard, Yakov Makarvovsky, Arthur L. LafleurAbstract:Fullerenes C60 and C70, generated by combustion, have been shown previously to be produced in controlled laminar flames accompanied by other compounds having Fullerene-like characteristics. Analysis of these additional compounds by high-performance liquid chromatography, coupled on-line with mass spectrometry has identified them as isomers of the C60 and C70 Fullerenes. The newly observed isomers have characteristic UV spectra and are thermally unstable, undergoing conversion to the more stable Fullerenes with a half-life of about 1 h in boiling toluene (111 degrees C). Isomers of C60 and C70 Fullerenes previously have been studied theoretically, but not observed experimentally. The flame-generated material also contains C60O and C70O compounds, as well as C76 and higher carbon clusters.
Rubén H. Contreras - One of the best experts on this subject based on the ideXlab platform.
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Density Functional Theory Calculation of Indirect Nuclear Magnetic Resonance Spin−Spin Coupling Constants in C70
Journal of the American Chemical Society, 2004Co-Authors: Juan E. Peralta, Veronica Barone, Gustavo E. Scuseria, Rubén H. ContrerasAbstract:We calculate NMR spin−spin coupling constants in the C70 Fullerene by means of density functional theory. We show that using a hybrid density functional (B3LYP) and an adequate basis set (cc-pCVDZ-sd), excellent agreement with experimental values can be achieved for one-bond couplings. These benchmark calculations suggest that theoretical predictions of NMR spin−spin couplings can be extremely valuable for discerning structural information of Fullerenes.