All Physics Faculty Presentations


Vibrational Dynamics and Structure of Graphitic Amorphous Carbon Using the Embedded Ring Approach

Document Type

Conference Paper

Journal/Book Title/Conference

American Ceramic Society Bulletin



Publication Date



The Raman spectrum of graphitic amorphous carbon (g-C) is modeled with simple classical methods, using rings as medium-range structural units. g-C provides a simple [nearly two dimensional (2D) with a single type of atom and one dominant bond type] prototypic example of a large class of continuous random network (CRN) solids where ring or cluster vibrations cannot be decoupled from the network in which they are embedded. We determined the in-plane vibrational modes of n=4, 5, 6, 7, and 8-membered symmetric, planar carbon rings using bond-stretching and bond-angle bending force constants; an additional force constant couples each ring node to the surrounding network. Our results support current models of g-C as small rafts of nearly 2D CRN’s comprised of ≊20% n=5, 60% n=6, and 20% n=7 rings, with very few n=4 and 8 rings. Extensions of the embedded-ring approach to more complex polyatomic and 3D CRN systems and to other probes of vibrational dynamics are discussed.


Am. Ceramic Society Bull. 79(3), 244 (1995). Invited talk at the 97th Annual Meeting of the American Ceramic Society, Cincinnati, OH

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