Raman spectroscopy of graphene and graphite: Disorder, electron phonon coupling, doping and nonadiabatic effects

Raman microspectroscopy of soot and related carbonaceous materials: Spectral analysis and structural information

We present a Raman study of Ar(+)-bombarded graphene samples with increasing ion doses. This allows us to have a controlled, increasing, amount of defects. We find that the ratio between the D and G peak intensities for a given defect density strongly depends on the laser excitation energy. We quantify this effect and present a simple equation for the determination of the point defect density in graphene via Raman spectroscopy for any visible excitation energy. We note that, for all excitations, the D to G intensity ratio reaches a maximum for an inter-defect distance ~3nm. Thus, a given ratio could correspond to two different defect densities, above or below the maximum. The analysis of the G peak width and its dispersion with excitation energy solves this ambiguity.

Quantifying defects in graphene via Raman spectroscopy at different excitation energies

We present a Raman study of Ar+-bombarded graphene samples with increasing ion doses. This allows us to have a controlled, increasing, amount of defects. We find that the ratio between the D and G peak intensities, for a given defect density, strongly depends on the laser excitation energy. We quantify this effect and present a simple equation for the determination of the point defect density in graphene via Raman spectroscopy for any visible excitation energy. We note that, for all excitations, the D to G intensity ratio reaches a maximum for an interdefect distance ∼3 nm. Thus, a given ratio could correspond to two different defect densities, above or below the maximum. The analysis of the G peak width and its dispersion with excitation energy solves this ambiguity.

/pdf/quantifying-defects-in-graphene-via-raman-spectroscopy-at-ni0uoxanyv.pdf

Quantifying defects in graphene via Raman spectroscopy at different excitation energies.

https://digital.csic.es/bitstream/10261/113789/1/Production_carbon_Sevilla.pdf

The production of carbon materials by hydrothermal carbonization of cellulose

Raman microprobe studies on carbon materials

This paper compares the information provided by X-ray diffraction and Raman spectrometry in terms of the structural order in a wide set of carbon solids. A special emphasis is placed in checking the validity of the commonly used formula of Tuinstra and Koenig and establishing the magnitude of errors potentially derived from its application. For this, a total number of 45 carbon materials aiming to cover the whole spectrum of properties and applications of these solids were jointly characterised by X-ray diffraction and Raman microprobe spectrometry. The comparison of d
 002
 interlayer spacing and the ratio of D to G Raman band intensities allows one to conclude that both techniques are complementary rather than equivalent. The different types of factors affecting the D and G band intensities and widths are discussed, it being concluded that their contributions are difficult to separate. The overall conclusion is that Tuinstra and Koenig's formula is valid only as a first approximation to L
 a
 values, and that errors as high as 100% are possible, so that, whenever feasible, direct measurements by XRD are recommended.

A. Cuesta

Papers

Raman microprobe studies on carbon materials

Comparative performance of X-ray diffraction and Raman microprobe techniques for the study of carbon materials