Raman Spectroscopy of Lattice-Matched Graphene on Strongly Interacting Metal Surfaces

Abstract

Regardless of the widely accepted opinion that there is no Raman signal from single-layer graphene when it is strongly bonded to a metal surface, we present Raman spectra of a graphene monolayer on Ni(111) and Co(0001) substrates. The high binding energy of carbon to these surfaces allows formation of lattice-matched (1 × 1) structures where graphene is significantly stretched. This is reflected in a record-breaking shift of the Raman G band by more than 100 cm relative to the case of freestanding graphene. Using electron diffraction and photoemission spectroscopy, we explore the aforementioned systems together with polycrystalline graphene on Co and analyze possible intercalation of oxygen at ambient conditions. The results obtained are fully supported by Raman spectroscopy. Performing a theoretical investigation of the phonon dispersions of freestanding graphene and stretched graphene on the strongly interacting Co surface, we explain the main features of the Raman spectra. Our results create a reliable platform for application of Raman spectroscopy in diagnostics of chemisorbed graphene and related materials.

Massive and massless charge carriers in an epitaxially strained alkali metal quantum well on graphene

“…1h. Unlike for epitaxial monolayer graphene on Co 46 and on Ir 15 with no or very weak 2D signal, the present epitaxial bilayer graphene sample shows a strong 2D signal when measured with blue or green light excitation (442 and 532 nm). The intensity of the 2D mode for ultraviolet (UV) excitation (325 nm) is much weaker in agreement with previous works 47 .…”

Gilding with Graphene: Rapid Chemical Vapor Deposition Synthesis of Graphene on Thin Metal Leaves

“…We find that graphene monolayers have a weak Raman signal, with no apparent D‐peaks, when supported on the Pd leaf. This is not surprising in light of the known strong binding between graphene monolayers and Pd . Accordingly, we transfer the graphene monolayers after synthesis via the electrochemical gas “bubbling” method to clean SiO 2 /Si substrates as presented in Figure e.…”

“…Importantly, it is mentioned earlier in this article that the Raman signal from monolayer graphene on the Pd leaf is weak. Specifically, CVD synthesized graphene strongly interacts with metal catalysts of the second group changing the G and 2D wavenumbers . Hybridization of the π orbitals of graphene and the d electrons of metals like Pd, Ni, and Ru modifies the Dirac cone, therefore suppresses the Raman scattering .…”

“…Specifically, CVD synthesized graphene strongly interacts with metal catalysts of the second group changing the G and 2D wavenumbers . Hybridization of the π orbitals of graphene and the d electrons of metals like Pd, Ni, and Ru modifies the Dirac cone, therefore suppresses the Raman scattering . In this study, we use 532 nm laser with exposure time of 30 s to collect the signal of graphene on Pd.…”

Investigation of optical fiber-tip probes for common and ultrafast SERS

“…Raman spectroscopy is a powerful technique for revealing intrinsic local chemical information in different types of systems, and is important in physics, material science, chemistry, biology, and medicine [1][2][3][4][5][6][7][8][9][10][11]. As spontaneous Raman signal is inherently weak, different types of Raman spectroscopy have been proposed and developed, such as surface-enhanced [12][13][14][15], tip-enhanced [16,17], femtosecond-stimulated [18][19][20], femtosecond time-resolved impulsive stimulated [21], polarized [22,23], and shifted excitation [24,25] Raman spectroscopy.…”