Heterogeneous reactions between solid substrates and solution phase reactants have seen increased interest in an effort to manipulate the properties of material surfaces and two-dimensional (2D) substrate materials. Such reactions result in covalently bound molecular species to the surface, where the surface properties become tunable based on the nature and concentration of molecular adsorbates. Control over degree of chemisorption on 2D substrates requires not only spatial characterization from local scanning probe microscopy methods (Fig.1 A&B), but also chemical characterization methods such as Raman spectroscopy to verify bond formation to the surface (Fig.1 C&D), using the D-band intensity at ~1334 cm<sup>-1</sup>. Here, we establish a quantitative link between these two characterization methods using electrochemically activated aryl diazonium chemistry (Fig.1 F). The degree of chemisorption on the graphite surface is altered by varying the concentration of species and the electrochemical activation parameters. High-resolution characterization with scanning tunneling microscopy provides quantitative reaction characterization at the surface, while Raman spectroscopy is employed to verify the chemisorbed nature (Fig.1 E). A quantitative model linking the spatial information (average inter-defect distance) and chemical information (D-band to G-band intensity ratio) is constructed. This work provides a fundamental contribution to characterization and understanding of chemically patterned surfaces.

Quantitative connections between Raman spectroscopy and scanning tunneling microscopy in chemisorption on graphite

253rd National Meeting (2017)

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