Observation of Electron-Phonon Couplings and Fano Re-sonances in Epitaxial Bilayer Graphene

Baranowski, J. M.; Możdżonek, M.; Dąbrowski, P.; Grodecki, K.; Osewski, P.; Kozlowski, W.; Kopciuszyński, M.; Strupiński, W.

doi:10.4236/graphene.2013.24017

Cited by 10 publications

(10 citation statements)

References 24 publications

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“…These values correspond to Raman shift energies of 130 and 43 cm −1 , in agreement with several DFT calculations [70]. The experimental evidence of the longitudinal mode was reported in ultrafast laser pump-probe spectroscopy [71] on FLG, at ∼ 120cm −1 , demonstrating also the presence there of the phonon and electron coupling through the Breit-Wigner-Fano resonance, as at more pronounced Gmode [72].…”

Section: Raman Shifts In Lbm and Shear Modes (C33 And C44 Elastic Consupporting

confidence: 88%

Van der Waals interlayer potential of graphitic structures: From Lennard–Jones to Kolmogorov–Crespy and Lebedeva models

Kozioł¹,

Gawlik²,

Jagielski³

2019

Chinese Phys. B

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The experimental knowledge on interlayer potential of graphenites is summarized and compared with computational results based on phenomenological models. Besides Lennard-Jones approximation, the Mie potential is discussed, Kolmogorov-Crespy model and equation of Lebedeva et al. An agreement is found between a set of reported physical properties of graphite (compressibility along c-axis under broad pressure range, Raman frequencies for bulk shear and breathing modes under pressure, layer binding energies), when a proper choice of model parameters is made. It is argued that the Kolmogorov-Crespy potential is the preferable one for modelling. A simple method of fast numerical modelling, convenient for accurate estimation of all these discussed physical properties is proposed. It is useful in studies of other van der Waals homo/heterostructures.

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Section: Raman Shifts In Lbm and Shear Modes (C33 And C44 Elastic Consupporting

confidence: 88%

Van der Waals interlayer potential of graphitic structures: From Lennard–Jones to Kolmogorov–Crespy and Lebedeva models

Kozioł¹,

Gawlik²,

Jagielski³

2019

Chinese Phys. B

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“…The observation of the peak, having a strong Fano line shape, in reflectivity, was discussed in the case of the hydrogenated graphene samples and was considered as a proof, of the successful hydrogenation of the graphene layers obtained on SiC(0001). 27 Therefore, the presence of a strong Fano line shape, in our intercalated sample, confirms the formation of the graphene bilayer as a result of the successful oxygen intercalation.…”

Section: Resultssupporting

confidence: 68%

“…The continuum responsible for the Fano resonances is attributed to the broad excitations, within the valence band of the bilayer graphene. 27 The ATR measurements, not discussed in the present work, show that the line at 1590 cm À1 is predominantly observed in s-polarization, which indicates that vibrations connected with the optical 1590 cm À1 mode are within the plane of the bilayer graphene. The observation of the peak, having a strong Fano line shape, in reflectivity, was discussed in the case of the hydrogenated graphene samples and was considered as a proof, of the successful hydrogenation of the graphene layers obtained on SiC(0001).…”

Section: Resultsmentioning

confidence: 89%

“…The spectacular effect of enhancing the phonon optical mode intensity, in the p-type epitaxial bilayer graphene, was recently reported and discussed. 27 The enhancement is due to the creation of a dimensionless, effective infrared charge, for the high doping levels. 28 In addition, the phonon peak observed in the reflectivity has a pronounced Fano line shape.…”

Section: Resultsmentioning

confidence: 99%

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New X-ray insight into oxygen intercalation in epitaxial graphene grown on 4H-SiC(0001)

Kowalski

Tokarczyk

Dąbrowski

et al. 2015

Journal of Applied Physics

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Efficient control of intercalation of epitaxial graphene by specific elements is a way to change properties of the graphene. Results of several experimental techniques, such as X-ray photoelectron spectroscopy, micro-Raman mapping, reflectivity, attenuated total reflection, X-ray diffraction, and X-ray reflectometry, gave a new insight into the intercalation of oxygen in the epitaxial graphene grown on 4H-SiC(0001). These results confirmed that oxygen intercalation decouples the graphene buffer layer from the 4H-SiC surface and converts it into the graphene layer. However, in contrast to the hydrogen intercalation, oxygen does not intercalate between carbon planes (in the case of few layer graphene) and the interlayer spacing stays constant at the level of 3.35–3.32 Å. Moreover, X-ray reflectometry showed the presence of an oxide layer having the thickness of about 0.8 Å underneath the graphene layers. Apart from the formation of the nonuniform thin oxide layer, generation of defects in graphene caused by oxygen was also evidenced. Last but not least, water islands underneath defected graphene regions in both intercalated and non-intercalated samples were most probably revealed. These water islands are formed in the case of all the samples stored under ambient laboratory conditions. Water islands can be removed from underneath the few layer graphene stacks by relevant thermal treatment or by UV illumination.

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“…The spectrum of CVD FLG on the copper substrate is largely featureless in the wavelength regions of interest, but importantly, no bands are present that would indicate graphene oxide (Figure S13A). Upon transfer of etched FLG from solution to the KBr substrate, an intense bipolar band centered at 1585 cm –1 appears because of a Fano resonance (Figure A). , Fano resonances arise in layered 2D systems from the in-plane optical phonon interactions between discrete and continuum states. Why these resonances appear on KBr but not on copper is unknown at this time.…”

Section: Resultsmentioning

confidence: 99%

Spontaneous Modification of Free-Floating Few-Layer Graphene by Aryldiazonium Ions: Electrochemistry, Atomic Force Microscopy, and Infrared Spectroscopy from Grafted Films

et al. 2016

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Free-floating, and copper-supported, few-layer graphene sheets were spontaneously modified from an aqueous solution containing nitrobenzenediazonium ions. The infrared spectra of the chemically modified (copper etched) free-floating graphene were measured in transmission mode by manipulating the sheets onto a KBr disc. The major advantage to this method is the ability to release the graphene sheets off the disc to refloat on a water bath, allowing the graphene to be further modified or deposited onto a new substrate suitable for other analysis. In this study, graphene sheets were then mounted onto highly ordered pyrolytic graphite (HOPG) for atomic force microscopy imaging and electrochemical measurements. The results show there are at least two reaction pathways for spontaneous film grafting to graphene: the commonly accepted aryl radical leading to films containing −C−C− linkages and a direct reaction of the diazonium cation with graphene to give films containing −NN− linkages. The ability to manipulate modified graphene sheets onto electrodes with two orientations, with the film exposed to electrolyte solution or sandwiched between graphene and HOPG, leads to different estimates of the surface concentration of electroactive groups. When the film is sandwiched between graphene and HOPG, two electroreduction signals for the nitro group are seen and much larger surface concentrations are measured. This is the first account of such a signal and is tentatively attributed to different peak potentials for reduction of nitro groups at graphene and HOPG. The solution permeability through the graphene sheet and attached films has important electrochemical consequences for systems of this type employed in supercapacitor applications.

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Observation of Electron-Phonon Couplings and Fano Re-sonances in Epitaxial Bilayer Graphene

Cited by 10 publications

References 24 publications

Van der Waals interlayer potential of graphitic structures: From Lennard–Jones to Kolmogorov–Crespy and Lebedeva models

Van der Waals interlayer potential of graphitic structures: From Lennard–Jones to Kolmogorov–Crespy and Lebedeva models

New X-ray insight into oxygen intercalation in epitaxial graphene grown on 4H-SiC(0001)

Spontaneous Modification of Free-Floating Few-Layer Graphene by Aryldiazonium Ions: Electrochemistry, Atomic Force Microscopy, and Infrared Spectroscopy from Grafted Films

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