Destruction of Multiwall Carbon Nanotubes under the Influence of Ion Bombardment
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Destruction of Multiwall Carbon Nanotubes under the Influence of Ion Bombardment Mariya M. Brzhezinskaya 1, Eugen M. Baitinger 1 and Vladimir V. Shnitov 2 Physics Department of Chelyabinsk State Pedagogical University, 69 Lenin Ave., Chelyabinsk 454080, Russia 2 Ioffe Physico-Technical Institute of the Russian Academy of Sciences, St. Petersburg 194021, Russia 1
ABSTRACT In this paper, the results of experiments on irradiation of the multiwall carbon nanotube (MWNT) samples by argon ions with energy of 1 keV are presented. They were obtained by energy loss spectroscopy of reflected electrons and Auger electron spectroscopy. It was found that ion irradiation of MWNTs decreases the characteristic energy and increases the full width at the half of the maximum (FWHM) of the π-plasmon peak. The plasmon relaxation time was found.
INRODUCTION Modification of carbon nanotubes by external factors makes possible to produce unique devices [1]. However, it is very important to control the degree of damage of the atomic structure and electron properties of carbon nanotubes. In this paper, the results of recent experiments on different doses of irradiation of the multiwall carbon nanotube (MWNT) samples with energy of 1 keV argon ions (Ar+) are presented. Energy electron loss spectroscopy (EELS) represents one of the effective methods for determining the degree of influence. Our experiments showed that EEL spectra are particularly sensitive to small doses at the beginning of the irradiation when the modification of carbon nanotube structure is not very significant. The π-plasmon energy Eπ and the full width at half maximum (FWHM) of the plasma peak δEπ were determined depending on dose of irradiation. The possible means for plasma peak widening as a result of the irradiation are discussed.
EXPERIMENTAL DETAILS MWNTs were prepared by the arc-discharge evaporation [2]. All samples were produced by the closed joint-stock company «Astrin», Saint-Peterburg, Russia. After the double-stage purification, the deposit consisted primarily of MWNTs. The MWNTs were 8 - 16 nm in diameter and approximately 10 µm in length. The experiments were carried out in the Ioffe Physico-Technical Institute of the Russian Academy of Sciences using ultra-high vacuum electron spectrometer with the multichannel energy analyzer [3]. This apparatus was designed to concurrently measure energy distribution of electrons emitted from a sample at eight different polar angles. The incident angle of the primary electron beam was Θ = 45°. The MWNT powder was mechanically deposited on ceramic substrates in the air and transferred into an ultra-high vacuum analytic chamber of the spectrometer. The vacuum system
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was then brought down to a pressure of 3⋅10-9 Torr. The vacuum chamber was baked out at a temperature of 150 °C for ten hours to remove traces of residual gases. After such treatment, Auger spectroscopy analysis proved satisfactory purity of the sample: carbon – 98%, oxygen – 0.8%, nitrogen – 0.7%, and sulfur – 0.7%. Then the sample was anneal
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