title: Enhancement of graphene visibility on transparent substrates by refractive index optimization.
abstract: Optical reflection microscopy is one of the main imaging tools to visualize graphene microstructures. Here is reported a novel method that employs refractive index optimization in an optical reflection microscope, which greatly improves the visibility of graphene flakes. To this end, an immersion liquid with a refractive index that is close to that of the glass support is used in-between the microscope lens and the support improving the contrast and resolution of the sample image. Results show that the contrast of single and few layer graphene crystals and structures can be enhanced by a factor of 4 compared to values commonly achieved with transparent substrates using optical reflection microscopy lacking refractive index optimization.
authors.affiliation: Department of Physics, University of Minho, Campus de Gualtar, Pt-4710-057 Braga, Portugal.
authors.forename: Hugo
authors.initials: H
authors.lastname: Gonçalves
authors.forename: Luís
authors.initials: L
authors.lastname: Alves
authors.forename: Cacilda
authors.initials: C
authors.lastname: Moura
authors.forename: Michael
authors.initials: M
authors.lastname: Belsley
authors.forename: Tobias
authors.initials: T
authors.lastname: Stauber
authors.forename: Peter
authors.initials: P
authors.lastname: Schellenberg
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D006108:Graphite / Q000032:analysis* / Q000737:chemistry; D008853:Microscopy / Q000295:instrumentation*; D053758:Nanoparticles / Q000032:analysis* / Q000648:ultrastructure*; D012031:Refractometry / Q000295:instrumentation*
chemical_list: D006108:Graphite