Terahertz time domain spectroscopy to detect low-frequency vibrations of double-walled carbon nanotubes

Kumar, Sunil ; Kamaraju, Natrajan ; Moravsky, Alexander ; Loutfy, R. O. ; Tondusson, Marc ; Freysz, Eric ; Sood, Ajay Kumar (2010) Terahertz time domain spectroscopy to detect low-frequency vibrations of double-walled carbon nanotubes European Journal of Inorganic Chemistry, 2010 (27). pp. 4363-4366. ISSN 1434-1948

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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/ejic.20...

Related URL: http://dx.doi.org/10.1002/ejic.201000524

Abstract

We have measured the frequency-dependent real index of refraction and extinction coefficient (and hence the complex dielectric function) of a free-standing double-walled carbon nanotube film of thickness 200 nm by using terahertz time domain spectroscopy in the frequency range 0.1 to 2.5 THz. The real index of refraction and extinction coefficient have very high values of approximately 52 and 35, respectively, at 0.1 THz, which decrease at higher frequencies. Two low-frequency phonon modes of the carbon nanotubes at 0.45 and 0.75 THz were clearly observed for the first time in the real and imaginary parts of the complex dielectric function along with a broad resonance centred at around 1.45 THz, the latter being similar to that in single-walled carbon nanotubes assigned to electronic excitations. Our experiments bring out a possible application of double-walled carbon nanotube films as a neutral density filter in the THz range.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
Keywords:Carbon; Nanotubes; Time-resolved Spectroscopy; Dielectric Function; Low-frequency Phonons
ID Code:50293
Deposited On:22 Jul 2011 14:03
Last Modified:22 Jul 2011 14:03

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