Resonance Raman spectroscopy in one-dimensional carbon materials

Abstract

Brazil has played an important role in the development and use of resonance Raman spectroscopy as a powerful characterization tool for materials science. Here we present a short history of Raman scattering research in Brazil, highlighting the important contributions to the field coming from Brazilian researchers in the past. Next we discuss recent and important contributions where Brazil has become a worldwide leader, that is on the physics of quasi-one dimensional carbon nanotubes. We conclude this article by presenting results from a very recent resonance Raman study of exciting new materials, that are strictly one-dimensional carbon chains formed by the heat treatment of very pure double-wall carbon nanotube samples.

Second‐order Raman scattering from linear carbon chains inside multiwalled carbon nanotubes

“…2,5 Moreover, the observation of a very strong L band signal in MWCNT, presented in this work, requires for its interpretation some peculiar scattering mechanism, and it can appear contradictory with other experimental observations and theoretical considerations. In fact, if the L bands of the linear chain inside MWCNT (present work) have the same nature and the same resonance profile as the CIM bands in DWCNT, experimentally measured for a wide excitation wavelength range, 8,9 the Raman scattering from L bands should be off resonance when excited by the 633 nm (1.96 eV) laser line (Fig. 2 of Ref.…”

“…7 Besides, an extensive investigation on the Raman resonance behaviour of the CIM bands revealed a prominent peak in the Raman resonance profile at 2.2 eV, and secondary maxima at about 2.4 and 2.6 eV. 8,9 These findings are quite different compared to the resonance behavior of the bands due to single-walled carbon nanotubes (SWCNT) and that of MWCNT, which show a broad resonance profile extended below 2 eV. 10,11 The occurrence of Raman active modes in the range 1780-1860 cm 1 has been also confirmed for MWCNT grown in a He atmosphere by using an arc discharge technique, in presence of pure carbon electrodes as well as in presence of a catalytic mixture.…”

Structure and Optical Properties of Carbon Nanoparticles Generated by Laser Treatment of Graphite in Liquids

“…The red shift of the diamond band observed in the sample prepared in DTPA (Figure b) compared to the bulk material (≈1324 cm −1 ) can be related to the decrease of the size of crystallites and is a common tendency for nanostructured materials. The feature at ≈1800 cm −1 in the Raman spectrum of NPs prepared in ethanol and DTPA can be attributed to the L band of linear carbon chains with a small and odd number of carbon atoms of sp hybridization …”

Effect of nanofiller concentration on its dispersion in a system of liquid crystalline SB(3R)-11 and single walled carbon nanotubes

“…This band gradually shifts with the concentration, so using the above equation one obtains a diameter of about 2.18 nm. The calculated value could be compared to the one, obtained from the radial breathing (RBM) mode (diameter of the pure SWCNTs), which ranges from about 1.09 to 1.85 nm (𝑑 𝑡 = 248/𝜔 𝑅𝐵𝑀 [21]). The difference could be used as a validation of the hypothesis of fibre formation (SWCNTs decorated with LC molecules).…”