Ambient exposure covers van der Waals materials with a self-assembled monolayer of normal alkanes, a form of contamination we previously identified using STM and infrared spectroscopy. In STM measurements of graphene and graphite, it has two clear fingerprints: it suppresses the phonon-induced tunneling gap and it produces an anomalously small current–distance decay constant.
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Our group has identified, using low temperature STM and infrared spectroscopy measurements, the structure and composition of the hydrocarbon contamination found on many van der Waals material surfaces (hBN, MoS2, etc.). When exposing fresh surfaces to ambient conditions, the initial contamination layer is replaced within days by a monolayer of straight chain alkanes. These alkanes […]
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In our recent paper published in Nature Nanotechnology, we show that the plasmon frequencies of graphene can be tuned from terahertz frequencies into the visible range. This enables extremely sensitive detection of molecules from femtomolar concentrations by Raman spectroscopy.
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