@article{c5ed0ab95f42412186a753845cf92b4b,
title = "Observation of an anomolously sharp feature in the 2nd order Raman spectrum of graphite",
abstract = "The second order Raman spectrum of graphite is shown to exhibit an anomolously sharp feature at an energy higher than twice the energy of the first order Raman line. This feature is compared to the 2667 cm-1 band in the second order Raman spectrum of diamond and is discussed in terms of a two-phonon bound state and ordinary overtone scattering. Also this feature serves to discriminate between current lattice dynamics calculations of graphite.",
author = "Nemanich, {R. J.} and Solin, {S. A.}",
note = "Funding Information: cm”1.The sharpness of the 3248 cm”{\textquoteright} feature may suggest that it is a first order Raman line that arises from impurities. While the temperature dependence of the intensity of a Raman feature can usually be used to distinguish the origin as to first or second order, this cannot be easily accomplished for modes with large Raman shifts. The most likely impurity to give rise to a mode near 3248 cm”1 would be hydrogen. Molecules with hydrogen bonded to a carbon atom which is triply bonded to another atom (e.g., HCN) yield a H-C mode at -{\textquoteleft}3300 cm”1 that would be Raman active{\textquoteright}7, however this configuration seems unlikely in graphite. Other configurations of H-C bonding yield bond stretching frequencies near 3000 cm”{\textquoteright} (e.g., benzene exhibits a mode at 3062 cm”{\textquoteright}).{\textquoteright}7 To further confirm that the 3248 cm”1 band is an intrinsic second order feature of graphite, we note its dependence on crystallite size.1418 Specifically that feature evolved from a sharp peak to a step drop with decreasing crystallite size in contrast to the behavior anticipated if the 3248 cm”{\textquoteright} band was a local impurity mode. The above arguments and the fact that the Raman spectra of HOPG and SCG are identical in our opinion supports the interpretation that the 3248 cm”1 mode is a *Research supported by the US ERDA. It has also benefitted from the general support of the University of Chicago Materials Research Laboratory by the NSF. **pr~ntaddress: Xerox Palo Alto Research Center, Palo Alto, California. ***A P. Sloan Foundation Fellow. Copyright: Copyright 2014 Elsevier B.V., All rights reserved.",
year = "1977",
month = aug,
doi = "10.1016/0038-1098(77)90998-X",
language = "English (US)",
volume = "23",
pages = "417--420",
journal = "Solid State Communications",
issn = "0038-1098",
publisher = "Elsevier Limited",
number = "7",
}