Electron spin resonance on single-walled carbon nanotubes obtained from different sources

Authors

  • Núria Ferrer-Anglada,

    Corresponding author
    1. Applied Physics Department, CRNE, Universitat Politècnica de Catalunya (UPC), Campus Nord B4, J. Girona 3-5, 08034 Barcelona, Spain
    • Phone: 0034 93 401 68 80, Fax: 0034 93 401 60 90
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  • Aida Abiad Monge,

    Corresponding author
    1. Applied Physics Department, CRNE, Universitat Politècnica de Catalunya (UPC), Campus Nord B4, J. Girona 3-5, 08034 Barcelona, Spain
    • Phone: 0034 93 401 68 80, Fax: 0034 93 401 60 90
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  • Siegmar Roth

    1. Max-Planck-Institut FKF, Heisenbergtr. 1, Stuttgart, Germany
    2. WCU, School of Electrical Engineering, Korea University, Seoul, Korea
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Abstract

We used electron spin resonance (ESR) to analyze several kinds of single-walled carbon nanotubes (SWNTs) synthesized by different methods. We observed that ESR is a sensitive probe that can be used to observe major differences between samples of carbon nanotubes (CNTs), in relation to their proportion of magnetic catalysts, impurities or defects. We analyzed the ESR spectra of CNTs in the usual way, by three overlapping lines. We then, implemented a function to fit the spectra, which gave us the intensity, line width (ΔHPP), and resonance line position (g factor) of each component line. The asymmetric line, which is assigned to the conduction electrons, could be used as a fingerprint of CNT purity. However, this asymmetric line is not always observed, since the three ESR lines often overlap, particularly when there is a large amount of paramagnetic ions. We studied the ESR spectra for different samples and estimated their purity by comparing the resulting parameters with data obtained by Raman spectroscopy on the same samples.

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