Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5141876 | Vibrational Spectroscopy | 2017 | 8 Pages |
Abstract
In this manuscript, we report the integrating a home-built scanning tunneling microscopy runner into a parabolic mirror assisted confocal optical microscope for performing high tip-enhanced Raman spectroscopy on graphene. To achieve an optimized optical excitation of the tip, a radially polarized laser beam is focused at the tip apex via a parabolic mirror. Graphene flakes grown on Cu foil are investigated. A decrease in the 2D peak intensity and increase of the G peak position indicate n-doping of the graphene flakes. The ultraviolet photoemission spectroscopy experiment shows that the underlying Cu foil induces a slight n-doping by raising the Fermi level by about 0.29Â eV as compared to the free-standing graphene. An increased electron concentration of about 0.6Â ÃÂ 1013Â cmâ2 can be derived from the tip-enhanced Raman spectra. A possible origin for the n-doping observed in the tip-enhanced Raman experiments, for example through the transfer of hot electrons from the excited Au tip to the graphene flake, is discussed.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Jan Rogalski, Kai Braun, Anke Horneber, Marius van den Berg, Johannes Uihlein, Heiko Peisert, Thomas Chassé, Alfred J. Meixner, Dai Zhang,