Interaction between edge-localized spins and molecular oxygen in multishell nanographites derived from nanodiamonds

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

doi:10.1016/j.diamond.2010.01.027

Interaction between edge-localized spins and molecular oxygen in multishell nanographites derived from nanodiamonds

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

Department of Physics

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

15 Scopus citations

Abstract

Adsorbed molecular oxygen significantly affects magnetic properties of nanographites. The present work reports on EPR study of multishell nanographite samples obtained from nanodiamonds by prolonged heat treatment. Remarkable differences in EPR spectra and temperature dependences of spectral parameters (integral intensity and linewidths) are observed for both well evacuated/annealed and air saturated samples. At room temperature (RT) air free samples show Lorentzian-like singlet lines narrowing on temperature decrease. RT spectra of oxygen rich samples demonstrate much broader asymmetric signals that, at lower temperatures, reveal superposition of broad (> 90%) and narrow (< 10%) lines. On cooling the broad component starts fast broadening whereas the narrow one remains of the same linewidth. Air free samples demonstrate saturation trend of peak intensities (I_pp) on microwave power (P) increase, whereas air rich samples reveal significant upward deviations from the non-saturating linear behavior in I_pp(sqrt(P)) plots - so-called "anti-saturation". This deviation occurs due to the narrowing of EPR lines on power rise. The effect may be interpreted in terms of selective and reversible removal of the main broadening agent - oxygen - from the location of uncoupled electron spins.

Original language	English
Pages (from-to)	492-495
Number of pages	4
Journal	Diamond and Related Materials
Volume	19
Issue number	5-6
DOIs	https://doi.org/10.1016/j.diamond.2010.01.027
State	Published - 1 May 2010

Keywords

EPR
Edge-localized states
Nanodiamonds
Nanotubes and fullerenes
Oxygen

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
General Chemistry
Mechanical Engineering
Materials Chemistry
Electrical and Electronic Engineering

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10.1016/j.diamond.2010.01.027

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title = "Interaction between edge-localized spins and molecular oxygen in multishell nanographites derived from nanodiamonds",

abstract = "Adsorbed molecular oxygen significantly affects magnetic properties of nanographites. The present work reports on EPR study of multishell nanographite samples obtained from nanodiamonds by prolonged heat treatment. Remarkable differences in EPR spectra and temperature dependences of spectral parameters (integral intensity and linewidths) are observed for both well evacuated/annealed and air saturated samples. At room temperature (RT) air free samples show Lorentzian-like singlet lines narrowing on temperature decrease. RT spectra of oxygen rich samples demonstrate much broader asymmetric signals that, at lower temperatures, reveal superposition of broad (> 90%) and narrow (< 10%) lines. On cooling the broad component starts fast broadening whereas the narrow one remains of the same linewidth. Air free samples demonstrate saturation trend of peak intensities (Ipp) on microwave power (P) increase, whereas air rich samples reveal significant upward deviations from the non-saturating linear behavior in Ipp(sqrt(P)) plots - so-called {"}anti-saturation{"}. This deviation occurs due to the narrowing of EPR lines on power rise. The effect may be interpreted in terms of selective and reversible removal of the main broadening agent - oxygen - from the location of uncoupled electron spins.",

keywords = "EPR, Edge-localized states, Nanodiamonds, Nanotubes and fullerenes, Oxygen",

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

note = "Funding Information: Authors thank Israeli Ministry of Science, Culture and Sport and Russian Foundation for Basic Research (MOST-RFBR grant# 3-5708 ; RFBR 09-02-92477-MNKSа ). ME acknowledges supports from the CLUSTER (the second stage) and Specially Promoted Research (No. 19002007 ) from the Ministry of Education, Culture, Sports, Science and Technology of Japan .",

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doi = "10.1016/j.diamond.2010.01.027",

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T1 - Interaction between edge-localized spins and molecular oxygen in multishell nanographites derived from nanodiamonds

AU - Osipov, V. Yu

AU - Shames, A. I.

AU - Enoki, T.

AU - Takai, K.

AU - Endo, M.

AU - Kaburagi, Y.

AU - Vul', A. Ya

N1 - Funding Information: Authors thank Israeli Ministry of Science, Culture and Sport and Russian Foundation for Basic Research (MOST-RFBR grant# 3-5708 ; RFBR 09-02-92477-MNKSа ). ME acknowledges supports from the CLUSTER (the second stage) and Specially Promoted Research (No. 19002007 ) from the Ministry of Education, Culture, Sports, Science and Technology of Japan .

PY - 2010/5/1

Y1 - 2010/5/1

N2 - Adsorbed molecular oxygen significantly affects magnetic properties of nanographites. The present work reports on EPR study of multishell nanographite samples obtained from nanodiamonds by prolonged heat treatment. Remarkable differences in EPR spectra and temperature dependences of spectral parameters (integral intensity and linewidths) are observed for both well evacuated/annealed and air saturated samples. At room temperature (RT) air free samples show Lorentzian-like singlet lines narrowing on temperature decrease. RT spectra of oxygen rich samples demonstrate much broader asymmetric signals that, at lower temperatures, reveal superposition of broad (> 90%) and narrow (< 10%) lines. On cooling the broad component starts fast broadening whereas the narrow one remains of the same linewidth. Air free samples demonstrate saturation trend of peak intensities (Ipp) on microwave power (P) increase, whereas air rich samples reveal significant upward deviations from the non-saturating linear behavior in Ipp(sqrt(P)) plots - so-called "anti-saturation". This deviation occurs due to the narrowing of EPR lines on power rise. The effect may be interpreted in terms of selective and reversible removal of the main broadening agent - oxygen - from the location of uncoupled electron spins.

AB - Adsorbed molecular oxygen significantly affects magnetic properties of nanographites. The present work reports on EPR study of multishell nanographite samples obtained from nanodiamonds by prolonged heat treatment. Remarkable differences in EPR spectra and temperature dependences of spectral parameters (integral intensity and linewidths) are observed for both well evacuated/annealed and air saturated samples. At room temperature (RT) air free samples show Lorentzian-like singlet lines narrowing on temperature decrease. RT spectra of oxygen rich samples demonstrate much broader asymmetric signals that, at lower temperatures, reveal superposition of broad (> 90%) and narrow (< 10%) lines. On cooling the broad component starts fast broadening whereas the narrow one remains of the same linewidth. Air free samples demonstrate saturation trend of peak intensities (Ipp) on microwave power (P) increase, whereas air rich samples reveal significant upward deviations from the non-saturating linear behavior in Ipp(sqrt(P)) plots - so-called "anti-saturation". This deviation occurs due to the narrowing of EPR lines on power rise. The effect may be interpreted in terms of selective and reversible removal of the main broadening agent - oxygen - from the location of uncoupled electron spins.

KW - EPR

KW - Edge-localized states

KW - Nanodiamonds

KW - Nanotubes and fullerenes

KW - Oxygen

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JO - Diamond and Related Materials

JF - Diamond and Related Materials

IS - 5-6

ER -

Interaction between edge-localized spins and molecular oxygen in multishell nanographites derived from nanodiamonds

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