Optical signatures of bulk and solutions of KC8 and KC24

Abstract

We first performed an analysis of the shape of the Raman features of potassium-intercalated graphite at stage 1 (KC 8 GIC) and 2 (KC 24 GIC), respectively. By varying the excitation energy from ultraviolet to infrared, we observed a sign change of the Fano coupling factor below and above the optical transition related to the shift of the Fermi level which was determined from first principle calculations. This behavior is explained by a sign change in the Raman scattering amplitude of the electronic continuum. The GICs were then dissolved in two different solvents (N-Methyl-2-pyrrolidone and tetrahydrofuran), and the absorbance of the graphenide solutions obtained was measured in the UV range. Two peaks were observed which correspond to the maximum of the computed imaginary part of the optical index. V C 2015 AIP Publishing LLC.

Solvent-driven electron trapping and mass transport in reduced graphites to access perfect graphene

“…After melting of potassium in the presence of graphite, the formation of a stage I GIC corresponding to KC 8 is verified by the characteristic broad Fano-line-shape spectrum of KC 8 ( Fig. 2c ) 27 28 . Besides the absence of any defect mode ∼1,330 cm − 1 , the G-mode is centred at 1,582 cm − 1 and therefore no residual doping is affecting the layers.…”

Resonance Raman Spectrum of Doped Epitaxial Graphene at the Lifshitz Transition

“…We have used a Fano line shape ,,, to fit the G band Raman spectra for all doping levels by Here I 0 is the Raman intensity, ω 0 the line position, γ the full-width at half-maximum, and 1/ q the asymmetry (or Fano) factor, which describes the strength of the interference effect between the discrete and continuous spectra. For 1/ q = 0, we have a Lorentzian line shape indicating no interference effect.…”

Theoretical study of polyiodide formation and stability on monolayer and bilayer graphene

“…34,35 This particular choice of exchange-correlation functional is based on previous works. 10,[36][37][38][39] For the sake of comparison, we have also computed the Tkatchenko-Scheffler (TS) method 40,41 for the adsorption of a single iodine molecule which is an interesting test case for describing the nonlocal anisotropic polarization. The vdW-TS-GGA (PBE functional) method predicts the same geometry properties and adsorption energy as the optB86b-vdW method, see Table S1 from the ESI.…”