Naslov
Electron loss and photoemission spectra in pristine and doped graphene

Autori
V. Despoja, D. Novko, L. Marušić, and M. Šunjić

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Skup
BRW-30th Brandt Ritchie Workshop

Mjesto i datum
Donostia-San Sebastián, Španjolska, 01.09.2013. - 04.09.2013

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Nije recenziran

Ključne riječi
graphene; X-ray; plasmons

Sažetak
Graphene linear dispersion and zero band gap structure near the Dirac point has the consequence that it supports (especially when it is doped) different collective and single particle electronic modes which all coexist in the same low energy region. This leads to its peculiar properties in external electromagnetic field. In this presentation we will consider graphene response to external moving or suddenly created point charge. The basic quantity in this investigation is the spectrum of graphene electronic excitations or the imaginary part of dynamically screened Coulomb interaction W. The propagator W is calculated in the framework of the first principle DFT-RPA formalism. The intensities of electronic excitations obtained from −ImW in doped graphene will be presented. The 2D plasmon dispersion curve (the low energy bright curve) is in good agreement with Das Sarma’s result and pi-plasmon linear dispersion (high energy bright curve) is in good agreement with recent experimental measurements. From these results we shall evaluate the potential induced by the point charge moving parallel to graphene plane. The induced bow waves in pristine graphene appear for higher velocities v > 2v_F and originate from excitation of pi plasmons. In doped graphene the induced bow waves appear at lower v_vF velocities and originate from the excitation of 2D plasmon. The spectra of core holes created in XPS experiment will also be presented. In pristine graphene, because of the zero gap, there exists a continuum of the low lying interband pi−pi* electron hole excitations causing asymmetrical lineshape, characteristic in normal metals. Doping opens two more excitation channels ; excitation of intraband pi−pi electron hole continuum and of 2D plasmons. This causes that the spectra become convolutions of the DS asymmetric line shape and strong multiple 2D plasmon peaks. This structure of the spectrum, more complex than in normal metals, is due to the fact that the Fermi and plasmon energies and the hole decay constant all have comparable values.

Izvorni jezik
Engleski

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