Overtone and combination features of G and D peaks in resonance Raman spectroscopy of the C78H26 polycyclic aromatic hydrocarbon. (26th June 2015)

• Record Type: Journal Article
• Authors: Maghsoumi, A.; Brambilla, L.; Castiglioni, C.; Müllen, K.; Tommasini, M.
• Is Part Of: Journal of Raman spectroscopy. Volume 46:Number 9(2015:Sep.)
• Page Start: 757
• Page End: 764
• Publication Date: 2015-06-26
• Subjects: Polycyclic Aromatic Hydrocarbon (PAH) -- Resonance Raman -- DFT -- graphene related materials; Raman spectroscopy -- Periodicals; 535.846
• DOI: 10.1002/jrs.4717
• Languages: English
• ISSNs: 0377-0486

Abstract

Abstract : We have studied the Raman spectra of C78 H26, a polycyclic aromatic hydrocarbon with D2h symmetry point group resembling a longitudinally confined graphene ribbon (or a graphene island) with armchair edge. The experimental spectra recorded with several excitation laser lines have been compared with the results from a theoretical analysis of the resonant Raman response based on density functional theory calculations. Compared to previous investigation the spectra show better signal‐to‐noise ratio, which allows determining previously unresolved weak spectroscopic features. We have extended our analysis to the overtone and combination region (i.e. above 2000 cm −1 ) demonstrating the presence of signals attributable to 2G, G + D, 2D, Dj + Dk and G + acoustic‐like modes. Moreover, we have measured the temperature dependence of the G peak position, which turns out to show a similar behavior with respect to that of graphene/graphite. Copyright © 2015 John Wiley & Sons, Ltd. Abstract : Raman spectra of the molecular graphene C78 H26 have been investigated in details both experimentally and theoretically. Overtones and combinations have been assigned. The G + D combination is proposed as probe of confinement in graphitic materials. The measure of the temperature dependence of the G peak provides a similar behavior with respect to that of graphene/graphite.