Optical Imaging and Spectroscopic Characterization of Self-Assembled Environmental Adsorbates on Graphene.
basic_science · Level V
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- Record sourced from PubMed, PMID 29589951.
- Also identified by DOI 10.1021/acs.nanolett.8b00348.
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Abstract
Topographic studies using scanning probes have found that graphene surfaces are often covered by micron-scale domains of periodic stripes with a 4 nm pitch. These stripes have been variously interpreted as structural ripples or as self-assembled adsorbates. We show that the stripe domains are optically anisotropic by imaging them using a polarization-contrast technique. Optical spectra between 1.1 and 2.8 eV reveal that the anisotropy in the in-plane dielectric function is predominantly real, reaching 0.6 for an assumed layer thickness of 0.3 nm. The spectra are incompatible with a rippled graphene sheet but would be quantitatively explained by the self-assembly of chainlike organic molecules into nanoscale stripes.