Photoinduced π- π* Band Gap Renormalization in Graphite

Stefania Pagliara, Gabriele Ferrini, Gianluca Galimberti, S Mor, M Montagnese, M. S. Grandi, P Galinetto, F. Parmigiani

Risultato della ricerca: Contributo in rivistaArticolo in rivistapeer review

17 Citazioni (Scopus)

Abstract

As is well-known, the character of the π orbitals is of paramount importance for the chemical properties of the carbon allotropes and their derived compounds. While at equilibrium the nature of these orbitals is well understood, their photoinduced nonequilibrium behavior is under investigation. Here, we demonstrate that when a UV-laser pulse excites a carrier density larger than 10% of the π* density of state in graphite, a renormalization of the π-π* band gap takes place. This result has been achieved by detecting the transient reflectivity and the associated decay time of an infrared probe following the excitation of a UV pump pulse tuned across the π-π* absorption resonance. The pump photon energy at which both the transient reflectivity and the decay time are maximum is downshifted by 500 meV with respect to the relative absorption maximum at equilibrium. This finding is interpreted as a transient π-π* band gap shrinking of similar magnitude, near the M point of the Brillouin zone.
Lingua originaleEnglish
pagine (da-a)6318-6322
Numero di pagine5
RivistaJournal of the American Chemical Society
Volume133
DOI
Stato di pubblicazionePubblicato - 2011

Keywords

  • Band gap renormalization
  • Grafite
  • Rinormalizzazione della gap
  • graphite

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