Electron Spectra Line Shape Analysis of Highly Oriented Pyrolytic Graphite and Nanocrystalline Diamond

Abstract

The X-ray excited Auger electron spectroscopy (XAES), X-ray photoelectron spectroscopy (XPS) and elastic peak electron spectroscopy (EPES) methods were applied in investigating samples of nanocrystalline diamond and highly oriented pyrolytic graphite of various C sp 2 /sp 3 ratios, crystallinity conditions and grain sizes. The composition at the surface was estimated from the XPS. The C sp 2 /sp 3 ratio was evaluated from the width of the XAES first derivative C KLL spectra and from fitting of XPS C 1s spectra into components. The pattern recognition (PR) method applied for analyzing the spectra line shapes exhibited high accuracy in distinguishing different carbon materials. The PR method was found to be a potentially useful approach for identification, especially important for technological applications in fields of materials engineering and for controlling the chemical reaction products during synthesis.

Unusual surface and edge morphologies, sp2 to sp3 hybridized transformation and electronic damage after Ar+ ion irradiation of few-layer graphene surfaces

“…The D values are within the reported values of 21 to 23 eV for HOPG (multi-layer graphene) [31], but not sensitive to the irradiation energy. However, comparison between the intensities of shoulder A and peak B reflects the sp 2 to sp 3 transition trend similar to that observed in Figure 7.…”

Multiwall carbon nanotubes purification and oxidation by nitric acid studied by the FTIR and electron spectroscopy methods

“…The accuracy of C sp 2 /sp 3 content evaluated from C 1s and C KLL spectra is limited, respectively, by the assumed BE and the parameter D values, Table 4 Comparison of FWHM of EPES and XPS spectra, and + loss peak energy shifts, ratio of area under loss peak of REELS and XPS EELS spectra recorded from "as-prepared" MWCNTs and oxidized MWCNTs. [33]. These values depend significantly on the sample cleanness, i.e.…”

“…oxygen contaminations and the proper content of the C sp 2 or sp 3 bonds in graphite and NCD, respectively. Also, the dependence of parameter D from clean graphite of different crystallinity and grain sizes was reported [33]. The worst accuracy for the C sp 2 content is evaluated from the REELS spectra, applying assumptions of only C sp 2 and C sp 3 bonds at the surface (Eq.…”

Understanding the intrinsic water wettability of graphite

“…Interestingly, the relationship of D-parameter on sp 2 /sp 3 hybridization is linear and can be interpolated to determine the relative amount of hybridization of a carbon sample. 337,[349][350][351][352] Taking the first derivative of the spectra in Figure 34a yields Figure 34b for ZYA and Figure 34c for PG. The D-parameter can be directly estimated from the graphs and was determined to be would have a single symmetric peak and α increases with amount of defects.…”