Theory of core-level spectra in x-ray photoemission of pristine and doped graphene

Despoja, Vito; Šunjić, Marijan

doi:10.1103/physrevb.88.245416

Cited by 14 publications

(17 citation statements)

References 30 publications

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“…In a recent work [18] one came to the same conclusion as we regarding the need to make a full calculation of the core-hole spectra in graphene instead of using the Doniach and Sunjić fitting of the peaks. They treated the band-structure of graphene in a different way compared to our and relied on density functional theory.…”

Section: Resultsmentioning

confidence: 89%

Core-level spectra from graphene

Sernelius

2015

Phys. Rev. B

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We calculate core-level spectra for pristine and doped free-standing graphene sheets. Instructions for how to perform the calculations are given in detail. Although pristine graphene is not metallic the core-level spectrum presents low-energy tailing which is characteristic of metallic systems. The peak shapes vary with doping level in a characteristic way. The spectra are compared to experiments and show good agreement. We compare to two different pristine samples and to one doped sample. The pristine samples are one with quasi-free-standing epitaxial graphene on SiC obtained by hydrogen intercalation and one with a suspended graphene sheet. The doped sample is a gold supported graphene sheet. The gold substrate acts as an acceptor so the graphene sheet gets p doped.

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Section: Resultsmentioning

confidence: 89%

Core-level spectra from graphene

Sernelius

2015

Phys. Rev. B

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“…The 2D plasmons give contribution from zero frequency and upward, which means that they contribute to the tail but also that no distinct plasmon loss replicas are distinguishable. If a constant 2D plasmon frequency is assumed discrete plasmon loss replicas are obtained 24 on top of a doping induced asymmetry, but such discrete loss structures are not observed in the experimental spectra. This point is illustrated in Fig.…”

Section: à2mentioning

confidence: 97%

Li induced effects in the core level and π-band electronic structure of graphene grown on C-face SiC

Johansson

Xia

Virojanadara

2015

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Studies of the effects induced in the electronic structure after Li deposition, and subsequent heating, on graphene samples prepared on C-face SiC are reported. The as prepared graphene samples are essentially undoped, but after Li deposition, the Dirac point shifts down to 1.2 eV below the Fermi level due to electron doping. The shape of the C 1s level also indicates a doping concentration of around 1014 cm−2 after Li deposition, when compared with recent calculated results of core level spectra of graphene. The C 1s, Si 2p, and Li 1s core level results show little intercalation directly after deposition but that most of the Li has intercalated after heating at 280 °C. Heating at higher temperatures leads to desorption of Li from the sample, and at 1030 °C, Li can no longer be detected on the sample. The single π-band observable from multilayer C-face graphene samples in conventional angle resolved photoelectron spectroscopy is reasonably sharp both on the initially prepared sample and after Li deposition. After heating at 280 °C, the π-band appears more diffuse and possibly split. The Dirac point becomes located at 0.4 eV below the Fermi level, which indicates occurrence of a significant reduction in the electron doping concentration. Constant energy photoelectron distribution patterns extracted from the as prepared graphene C-face sample and also after Li deposition and heating at 280 °C look very similar to earlier calculated distribution patterns for monolayer graphene.

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“…The core level binding energy is then computed from the total energy difference between a calculation with the core hole and a ground state calculation. More advanced methods aimed at directly simulating the dynamical screening of the core hole and thus the lifetimes and resulting line shapes have also been developed [ 53 – 55 ]. However, since the topic of calculating the core level binding energies in doped carbon nanomaterials is an active area of our research, we will for brevity leave a more detailed discussion of the topic for a later time.…”

Section: Reviewmentioning

confidence: 99%

X-ray photoelectron spectroscopy of graphitic carbon nanomaterials doped with heteroatoms

Susi¹,

Pichler²,

Ayala³

2015

Beilstein J. Nanotechnol.

355

258

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SummaryX-ray photoelectron spectroscopy (XPS) is one of the best tools for studying the chemical modification of surfaces, and in particular the distribution and bonding of heteroatom dopants in carbon nanomaterials such as graphene and carbon nanotubes. Although these materials have superb intrinsic properties, these often need to be modified in a controlled way for specific applications. Towards this aim, the most studied dopants are neighbors to carbon in the periodic table, nitrogen and boron, with phosphorus starting to emerge as an interesting new alternative. Hundreds of studies have used XPS for analyzing the concentration and bonding of dopants in various materials. Although the majority of works has concentrated on nitrogen, important work is still ongoing to identify its precise atomic bonding configurations. In general, care should be taken in the preparation of a suitable sample, consideration of the intrinsic photoemission response of the material in question, and the appropriate spectral analysis. If this is not the case, incorrect conclusions can easily be drawn, especially in the assignment of measured binding energies into specific atomic configurations. Starting from the characteristics of pristine materials, this review provides a practical guide for interpreting X-ray photoelectron spectra of doped graphitic carbon nanomaterials, and a reference for their binding energies that are vital for compositional analysis via XPS.

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Theory of core-level spectra in x-ray photoemission of pristine and doped graphene

Cited by 14 publications

References 30 publications

Core-level spectra from graphene

Core-level spectra from graphene

Li induced effects in the core level and π-band electronic structure of graphene grown on C-face SiC

X-ray photoelectron spectroscopy of graphitic carbon nanomaterials doped with heteroatoms

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