Publications (3)17.04 Total impact
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Article: Graphene as a transparent conductive support for studying biological molecules by transmission electron microscopy
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ABSTRACT: We demonstrate the application of graphene as a support for imaging individual biological molecules in transmission electron microscope (TEM). A simple procedure to produce free-standing graphene membranes has been designed. Such membranes are extremely robust and can support practically any sub-micrometer object. Tobacco mosaic virus has been deposited on graphene samples and observed in a TEM. High contrast has been achieved even though no staining has been applied.Applied Physics Letters 10/2010; 97(15):153102. · 3.84 Impact Factor -
Article: On resonant scatterers as a factor limiting carrier mobility in graphene.
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ABSTRACT: We show that graphene deposited on a substrate has a non-negligible density of atomic scale defects. This is evidenced by a previously unnoticed D peak in the Raman spectra with intensity of ∼1% with respect to the G peak. We evaluated the effect of such impurities on electron transport by mimicking them with hydrogen adsorbates and measuring the induced changes in both mobility and Raman intensity. If the intervalley scatterers responsible for the D peak are monovalent, their concentration is sufficient to account for the limited mobilities currently achievable in graphene on a substrate.Nano Letters 10/2010; 10(10):3868-72. · 13.20 Impact Factor -
Article: Spectroscopic ellipsometry of graphene and an exciton-shifted van Hove peak in absorption
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ABSTRACT: We demonstrate that optical transparency of any two-dimensional system with a symmetric electronic spectrum is governed by the fine structure constant and suggest a simple formula that relates a quasi-particle spectrum to an optical absorption of such a system. These results are applied to graphene deposited on a surface of oxidized silicon for which we measure ellipsometric spectra, extract optical constants of a graphene layer and reconstruct the electronic dispersion relation near the K point using optical transmission spectra. We also present spectroscopic ellipsometry analysis of graphene placed on amorphous quartz substrates and report a pronounced peak in ultraviolet absorption at 4.6 eV because of a van Hove singularity in graphene's density of states. The peak is downshifted by 0.5 eV probably due to excitonic effects. Comment: 14 pages, 5 figures, accepted to Phys Rev B03/2010;
