Spin-spin interactions between π-electronic edge-localized spins and molecular oxygen in defective carbon nano-onions

A. I. Shames; V. Yu Osipov; A. Ya Vul'; Y. Kaburagi; T. Hayashi; K. Takai; T. Enoki

doi:10.1016/j.carbon.2013.04.082

Spin-spin interactions between π-electronic edge-localized spins and molecular oxygen in defective carbon nano-onions

A. I. Shames, V. Yu Osipov, A. Ya Vul', Y. Kaburagi, T. Hayashi, K. Takai, T. Enoki

Department of Physics

Ben-Gurion University of the Negev

Research output: Contribution to journal › Article › peer-review

Abstract

π-Electronic edge-localized spin magnetism in defective carbon nano-onions (DCNOs) derived from detonation nanodiamonds was investigated in terms of molecular oxygen adsorption and microwave (MW) irradiation effect. At low MW power (P_MW ≤ 200 μW) electron paramagnetic resonance (EPR) spectra of air-contained DCNO samples show progressive broadening of the g = 2.0014(2) edge-spin signal on temperature decrease. Below 140 K, the edge-spin signal becomes unobservable and the only weak narrow g = 2.0022(1) signal ascribed to sp³-like defects is observed. Upon higher power (P_MW > 20 mW) MW-irradiation at T < 60 K, that weak signal demonstrates unusual enhancement in peak/integral intensities and line broadening accompanied with upward deviations from the conventional saturation behavior. On abrupt reduction of P_MW to low (P_MW < 1 mW) levels, a new strong narrow signal with the same g = 2.0022(1) emerges. Below 60 K the intensity of the strong signal shows non-Curie-Weiss behavior. This EPR signal is attributed to new magnetic entities originating from antiferromagnetically coupled dimers of edge-spin and negatively charged O ₂^- molecule. The O₂^- molecules, formed by charge transfer from π-electronic reservoir of underlaid nano-graphene sheet, appear in the vicinity of nano-graphene edges in the process of desorption/adsorption of oxygen molecules caused by strong MW-irradiation and subsequent abrupt reduction of P_MW.

Original language	American English
Pages (from-to)	173-189
Number of pages	17
Journal	Carbon
Volume	61
DOIs	https://doi.org/10.1016/j.carbon.2013.04.082
State	Published - 1 Sep 2013

All Science Journal Classification (ASJC) codes

General Chemistry
General Materials Science

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10.1016/j.carbon.2013.04.082

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@article{ab7a87b3c9f84eee894af979666124b5,

title = "Spin-spin interactions between π-electronic edge-localized spins and molecular oxygen in defective carbon nano-onions",

abstract = "π-Electronic edge-localized spin magnetism in defective carbon nano-onions (DCNOs) derived from detonation nanodiamonds was investigated in terms of molecular oxygen adsorption and microwave (MW) irradiation effect. At low MW power (PMW ≤ 200 μW) electron paramagnetic resonance (EPR) spectra of air-contained DCNO samples show progressive broadening of the g = 2.0014(2) edge-spin signal on temperature decrease. Below 140 K, the edge-spin signal becomes unobservable and the only weak narrow g = 2.0022(1) signal ascribed to sp3-like defects is observed. Upon higher power (PMW > 20 mW) MW-irradiation at T < 60 K, that weak signal demonstrates unusual enhancement in peak/integral intensities and line broadening accompanied with upward deviations from the conventional saturation behavior. On abrupt reduction of PMW to low (PMW < 1 mW) levels, a new strong narrow signal with the same g = 2.0022(1) emerges. Below 60 K the intensity of the strong signal shows non-Curie-Weiss behavior. This EPR signal is attributed to new magnetic entities originating from antiferromagnetically coupled dimers of edge-spin and negatively charged O 2- molecule. The O2- molecules, formed by charge transfer from π-electronic reservoir of underlaid nano-graphene sheet, appear in the vicinity of nano-graphene edges in the process of desorption/adsorption of oxygen molecules caused by strong MW-irradiation and subsequent abrupt reduction of PMW.",

author = "Shames, {A. I.} and Osipov, {V. Yu} and Vul', {A. Ya} and Y. Kaburagi and T. Hayashi and K. Takai and T. Enoki",

note = "Funding Information: The present work was supported by JSPS and RFBR under the Japan–Russia Research Cooperative Program within the grants: RFBR 12-02-92107 ЯФ_а and JSPS (“Magnetic interactions in the system of edge-localized spins in nano-graphene derived from nanodiamonds”). A.Ya.V. thanks the Programs of the Russian Academy of Sciences for support. The present work was also supported by the Grant-in-aid for Scientific Research No. 20001006 from the Ministry of Education, Culture, Sports, Science and Technology of Japan. Authors express their gratitude to Prof. Yoshihiro Hishiyama (former Musashi Institute of Technology, Tokyo, Japan) for proposal and construction the special design of quick-acting electrical furnace used in this study. V.Yu.O. thanks the Department of Chemistry of Tokyo Institute of Technology for possibility to use their technological and experimental equipment.",

year = "2013",

month = sep,

day = "1",

doi = "10.1016/j.carbon.2013.04.082",

language = "American English",

volume = "61",

pages = "173--189",

journal = "Carbon",

issn = "0008-6223",

publisher = "Elsevier Ltd.",

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TY - JOUR

T1 - Spin-spin interactions between π-electronic edge-localized spins and molecular oxygen in defective carbon nano-onions

AU - Shames, A. I.

AU - Osipov, V. Yu

AU - Vul', A. Ya

AU - Kaburagi, Y.

AU - Hayashi, T.

AU - Takai, K.

AU - Enoki, T.

N1 - Funding Information: The present work was supported by JSPS and RFBR under the Japan–Russia Research Cooperative Program within the grants: RFBR 12-02-92107 ЯФ_а and JSPS (“Magnetic interactions in the system of edge-localized spins in nano-graphene derived from nanodiamonds”). A.Ya.V. thanks the Programs of the Russian Academy of Sciences for support. The present work was also supported by the Grant-in-aid for Scientific Research No. 20001006 from the Ministry of Education, Culture, Sports, Science and Technology of Japan. Authors express their gratitude to Prof. Yoshihiro Hishiyama (former Musashi Institute of Technology, Tokyo, Japan) for proposal and construction the special design of quick-acting electrical furnace used in this study. V.Yu.O. thanks the Department of Chemistry of Tokyo Institute of Technology for possibility to use their technological and experimental equipment.

PY - 2013/9/1

Y1 - 2013/9/1

N2 - π-Electronic edge-localized spin magnetism in defective carbon nano-onions (DCNOs) derived from detonation nanodiamonds was investigated in terms of molecular oxygen adsorption and microwave (MW) irradiation effect. At low MW power (PMW ≤ 200 μW) electron paramagnetic resonance (EPR) spectra of air-contained DCNO samples show progressive broadening of the g = 2.0014(2) edge-spin signal on temperature decrease. Below 140 K, the edge-spin signal becomes unobservable and the only weak narrow g = 2.0022(1) signal ascribed to sp3-like defects is observed. Upon higher power (PMW > 20 mW) MW-irradiation at T < 60 K, that weak signal demonstrates unusual enhancement in peak/integral intensities and line broadening accompanied with upward deviations from the conventional saturation behavior. On abrupt reduction of PMW to low (PMW < 1 mW) levels, a new strong narrow signal with the same g = 2.0022(1) emerges. Below 60 K the intensity of the strong signal shows non-Curie-Weiss behavior. This EPR signal is attributed to new magnetic entities originating from antiferromagnetically coupled dimers of edge-spin and negatively charged O 2- molecule. The O2- molecules, formed by charge transfer from π-electronic reservoir of underlaid nano-graphene sheet, appear in the vicinity of nano-graphene edges in the process of desorption/adsorption of oxygen molecules caused by strong MW-irradiation and subsequent abrupt reduction of PMW.

AB - π-Electronic edge-localized spin magnetism in defective carbon nano-onions (DCNOs) derived from detonation nanodiamonds was investigated in terms of molecular oxygen adsorption and microwave (MW) irradiation effect. At low MW power (PMW ≤ 200 μW) electron paramagnetic resonance (EPR) spectra of air-contained DCNO samples show progressive broadening of the g = 2.0014(2) edge-spin signal on temperature decrease. Below 140 K, the edge-spin signal becomes unobservable and the only weak narrow g = 2.0022(1) signal ascribed to sp3-like defects is observed. Upon higher power (PMW > 20 mW) MW-irradiation at T < 60 K, that weak signal demonstrates unusual enhancement in peak/integral intensities and line broadening accompanied with upward deviations from the conventional saturation behavior. On abrupt reduction of PMW to low (PMW < 1 mW) levels, a new strong narrow signal with the same g = 2.0022(1) emerges. Below 60 K the intensity of the strong signal shows non-Curie-Weiss behavior. This EPR signal is attributed to new magnetic entities originating from antiferromagnetically coupled dimers of edge-spin and negatively charged O 2- molecule. The O2- molecules, formed by charge transfer from π-electronic reservoir of underlaid nano-graphene sheet, appear in the vicinity of nano-graphene edges in the process of desorption/adsorption of oxygen molecules caused by strong MW-irradiation and subsequent abrupt reduction of PMW.

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U2 - 10.1016/j.carbon.2013.04.082

DO - 10.1016/j.carbon.2013.04.082

M3 - Article

SN - 0008-6223

VL - 61

SP - 173

EP - 189

JO - Carbon

JF - Carbon

ER -

Spin-spin interactions between π-electronic edge-localized spins and molecular oxygen in defective carbon nano-onions

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