Raman Spectroscopy of Graphitic Nanomaterials (original) (raw)
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Temperature-Dependent Raman Spectroscopy of Graphitic Nanomaterials
2019
The sp2 carbonaceous molecules possess a single atomic type per unit cell, which makes these materials very good candidates for quantum mechanical studies associated with their vibrational and electronic energy levels. Significant findings, such as the Kohn anomaly, electron-phonon interactions, and other exciton-related effects, associated with these molecules can be transported to other 2-D materials. Information derived from the distinctive Raman bands from a single layer of carbon atoms also aids in gaining insight into new physics from such materials and other graphitic nanomaterials. The present paper focuses on our investigations of the G, D, and G′ bands of graphene and graphite, and the specific information provided by each. The G-band peak located at ~1586 cm−1, shared by all sp2 carbons, has been used by us extensively in the estimation of thermal conductivity and thermal expansion characteristics linked to single-walled carbon nanotubes. In addition, we have investigated...
Raman Spectroscopy of Graphene, Graphite and Graphene Nanoplatelets
2D Materials, 2019
The theoretical simplicity of sp 2 carbons, owing to their having a single atomic type per unit cell, makes these materials excellent candidates in quantum chemical descriptions of vibrational and electronic energy levels. Theoretical discoveries, associated with sp 2 carbons, such as the Kohn anomaly, electron-phonon interactions, and other exciton-related effects, may be transferred to other potential 2D materials. The information derived from the unique Raman bands from a single layer of carbon atoms also helps in understanding the new physics associated with this material, as well as other two-dimensional materials. The following chapter describes our studies of the G, D, and G′ bands of graphene and graphite, and the characteristic information provided by each material. The G-band peak located at ~1586 cm −1 , common to all sp 2 carbons, has been used extensively by us in the estimation of thermal conductivity and thermal expansion characteristics of the sp 2 nanocarbon associated with single walled carbon nanotubes (SWCNT). Scanning electron microscope (SEM) images of functionalized graphene nanoplatelet aggregates doped with argon (A), carboxyl (B), oxygen (C), ammonia (D), fluorocarbon (E), and nitrogen (F), have also been recorded and analyzed using the Gwyddion software.
Dispersive Raman spectra observed in graphite and single wall carbon nanotubes
Physica B: Condensed Matter, 2002
The disorder-induced D-band and some other non-zone center Raman modes of graphite and single wall carbon nanotubes are assigned to phonon modes in their respective Brillouin zones. In disordered graphite, the weak, dispersive phonon modes, which have been known but never assigned so far, are well described by the double resonance Raman process. All weak Raman peaks observed for sp 2 carbons are useful for determining the phonon dispersion relations of graphite. In carbon nanotubes, all semiconducting nanotubes and some metallic nanotubes have van Hove singular k points for their electronic and phonon energy dispersion curves at the G point of the Brillouin zone. A corresponding Raman process is relevant to explain the observed D-band and intermediate frequency spectra. r
Characterization of carbon nanotubes by Raman spectroscopy
MATERIALS SCIENCE-POLAND
Application of Raman spectroscopy to analyse carbon nanotubes has been presented. Having a mixture of various carbon nanotube samples, one can easily distinguish, in a quick experiment, presence of singlewalled, doublewalled and multiwalled carbon nanotubes (SWCNT, DWCNT, MWCNT, respectively). The so-called G-line is a characteristic feature of the graphitic layers and corresponds to the tangential vibration of carbon atoms. Another characteristic mode is a typical sign of defective graphitic structures (D-line). A comparison of the intensity ratios of these two peaks gives a measure of the quality of the bulk samples. In addition, there is a third mode, named the radial breathing mode (RBM) which is very sensitive to the diameter of SWCNT and DWCNT. Additional option is application of Raman microscopy for mapping analysis and depth profiling to view the changes of intensity in various directions in the sample.
2022
Graphene nanoplatelets (GnPs) are promising candidates for gas sensing applications because they have a high surface area to volume ratio, high conductivity, and a high temperature stability. Also, they cost less to synthesize, and they are lightweight, making them even more attractive than other 2D carbon-based materials. In this paper, the surface and structural properties of pristine and functionalized GnPs, specifically with carboxyl, ammonia, carboxyl, nitrogen, oxygen, fluorocarbon, and argon, were examined with Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction (XRD) to determine the functional groups present and effects of those groups on the structural and vibrational properties. We attribute certain features in the observed Raman spectra to the variations in concentration of the functionalized GnPs. XRD results show smaller crystallite sizes for functionalized GnPs samples that agree with images acquired with...
Physical Chemistry Chemical Physics, 2012
Raman spectroscopy has been already established as a powerful tool for characterizing the different types of carbon nanostructures, ranging from the highly ordered two-dimensional graphene and one-dimensional nanotubes, down to disordered materials, like nanographite and charcoal. Here we focus on the recent advances of Raman spectroscopy within carbon nanoscience. We discuss in situ nano-manipulation and Raman imaging for addressing controlled perturbations; multi-technique work for the development of nanometrology; crossing the diffraction limit with near-field optics for high resolution imaging. Finally, the applications of Raman spectroscopy in cross-referenced fields, like biotechnology and soil science, are discussed.
A comparison between Raman spectroscopy and surface characterizations of multiwall carbon nanotubes
Carbon, 2006
The distribution of graphene units with an axial symmetry gives rise to different types of carbon filaments: nanotubes, nanofilaments and classical fibers. In this work the surfaces of different multiwalled nanotubes are characterized by two complementary techniques: chemical ones based on Total Surface Area and Active Surface Area measurements, associated with a physical approach the Raman scattering spectroscopy. From analysis of Raman data we deduce the values of the in-plane coherence lengths, identified as L 1 the planar projection of graphene sheets, and we propose an analysis for the observed line-width behavior related to the graphitization step. From the surface chemical properties we establish a general relationship between the density of functional surface groups and the in plane coherence length L 1 for all types of MWNT. This analysis allows us to show the influence of both, the structural organization and the different treatments on the interfacial characteristics of these nanocarbons.