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We present Raman spectra of epitaxial graphene layers grown on 63×63 reconstructed silicon carbide surfaces during annealing at elevated temperature. In contrast to exfoliated graphene a significant phonon hardening is observed. We ascribe that phonon hardening to a minor part to the known electron transfer from the substrate to the epitaxial layer, and mainly to mechanical strain that builds up when the sample is cooled down after annealing. Due to the larger thermal expansion coefficient of silicon carbide compared to the in-plane expansion coefficient of graphite this strain is compressive at room temperature.

Single‐layer graphene (SLG) is deposited onto Si/SiO2 substrates from aqueous dispersions using a scalable and quick detergent‐based method (see figure). The deposits are analyzed using absorption and Raman spectroscopy and atomic force and optical microscopy. Evaluation of the two‐phonon defect‐induced Raman peak of individual particles on the substrate is used to confirm exfoliation into graphene monolayers.

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A new reaction sequence for the chemical functionalization of single-wall carbon nanotubes (SWNTs) consisting of the nucleophilic addition of t-BuLi to the sidewalls of the tubes and the subsequent reoxidation of the intermediates t-Bu(n)SWNT(n-) leading to t-Bu(n)SWNT was developed. During the formation of the t-Bu(n)SWNT(n-), a homogeneous dispersion in benzene was formed due to the electrostatic repulsion of the negatively charged intermediates causing debundling. The entire reaction sequence can be repeated, and the degree of functionalization of the products (t-Bu(n))(m)SWNT (m = 1-3) increases with increasing m. Degrees of functionalization expressed as the carbon-to-addend ratio of up to 31 were reached. The reaction was studied in detail by photoelectron spectroscopy, Raman spectroscopy, and scanning tunneling microscopy (STM). The C 1s core level spectra reveal that the nucleophilic attack of the t-BuLi leads to negatively charged SWNTs. Upon oxidation, this negative charge is removed. The valence band spectra of the functionalized samples exhibit a significant reduction in the pi-derived density of states. In STM, the covalently bonded t-butyl groups attached to the sidewalls have been visualized. Raman spectroscopy reveals that addition of the nucleophile to metallic tubes is preferred over the addition to semiconducting tubes.