Raman scattering from intercalated donor compounds of graphite

Journal Article · Thu Sep 15 04:00:00 EDT 1977 · Phys. Rev., B; (United States)

DOI:https://doi.org/10.1103/PhysRevB.16.2965· OSTI ID:7289856

Nemanich, R J; Solin, S A; Guerard, D

Raman spectra of vibrational excitations in graphite intercalated with alkali donor atoms have been obtained at room temperature in the backscattering configuration using argon-ion excitation. Stage 1, 2, and 3 cesium donor compounds prepared from highly oriented pyrolytic graphite (HOPG) were studied as were stage 1 and 2 HOPG potassium donor compounds. Second-state cesium and potassium intercalated exhibit a single Raman band unshifted from the E/sub 2g/ intralayer mode of HOPG which occurs at 1582 cm/sup -1/. In contrast, the third-stage cesium intercalate produces a doublet spectrum with one component upshifted from and the other at the same position at HOPG intralayer mode. The above described observations for stage-2 and higher-stage donor compounds are explained by an analysis which considers (a) the nearest-layer configurations which a given carbon layer can experience in a given stage of intercalation, (b) the change in C-C bond distance with intercalation, and (c) the effect of intercalation on the carbon interlayer interaction. The spectra of stage-1 cesium and potassium intercalates are almost identical and each contains two anomolously shaped bands, one near to but down shifted from the interlayer mode of HOPG and one at approx. 560 cm/sup -1/, both being superposed on a continuum background. These bands are attributed to Breit-Wigner or Fano resonances between an electronic Raman scattering continuum and the E/sub 2g/ intralayer mode and an out of plane intralayer vibration, respectively. The parameters GAMMA, q, and Omega-bar governing the Breit-Wigner resonance are determined by fitting the observed line shapes of each of the two bands in the cesium and potassium intercalate spectra.

• Research Organization: The Department of Physics and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637
• OSTI ID: 7289856
• Journal Information: Phys. Rev., B; (United States), Journal Name: Phys. Rev., B; (United States) Vol. 16:6; ISSN PLRBA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ALLOYS
CARBON
CESIUM ADDITIONS
CESIUM ALLOYS
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
GRAPHITE
LAMELLAE
NONMETALS
POTASSIUM ADDITIONS
POTASSIUM ALLOYS
RAMAN SPECTRA
SPECTRA