Volume206, number 1,2,3,4 CHEMICALPHYSICSLETTERS 30 April 1993 Vibrational mode frequencies in CT0 R.A. Jishi Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA and Department of Physics, California State University, Los Angeles, CA 90032, USA M.S. Dresselhaus Department OfElectrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge> MA 02139, USA andDepartment ofPhysics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA G. Dresselhaus Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA IQ&AnWang,Ping Zhou, A.M. Rao and P.C. Eklund Department of Physics, University of Kentucky, Lexington, KY40506 USA Received 29 December 1992; in final form 17 February 1993 Raman scattering measurements yielding 26 vibrational mode frequencies, along with their depolarization ratios, are reported. A force-constant model, originally developed for CM), is extended to CT0 and is shown to result in good agreement with these measurements using two adjustable parameters to fit 26 observed Raman and 16 infrared modes. In the production of fullerenes, appreciable amounts of C,. are produced in addition to Cso [ 1,2]. The CT0 molecule shown in fig. 1 has DSh geometry [ 3,4] with a belt of ten carbon atoms located in be- tween the two hemispherical caps that constitute the ChO molecule. As shown in fig. 1 the belt plane is per- pendicular to a five-fold symmetry axis. Indeed, nu- Fig. 1. Structure of the Cl0 molecule showing D, symmetry. clear magnetic resonance (NMR) measurements are consistent with this structure, showing a spectrum with five lines; the chemical shift corresponding to the belt atoms is well separated from that of the other carbon atoms [ $6 1. Due to the lower symmetry of C70 in comparison to Ceo, there are many more infrared and Raman-ac- tive modes in C,, than in Ceo. Group theoretical analysis [ 71 indicates that C,. has 53 Raman-active modes and 31 infrared-active modes. The Raman- active modes correspond to the symmetry types 12A; t 22E5 + 19EY, where the A’, modes are ob- served in the (II, II), the E; in the (11, I), and the E; in both (II, (I ) and (II, I) polarization geome- tries. The infrared-active modes transform accord- ing to the irreducible representations A; and E; and in CT0 we have lOA’;+2 lE’, infrared-active modes [ 7 1. In measurements using polarized light, the fre- quencies of 2 1 Raman-active modes were measured along with the intensity ratios for ( (1, 11) and (I(, I ) geometries [ 81, and 16 infrared-active modes were 0009-2614/93/$ 06.00 0 1993 Elsevier Science Publishers B.V. All rights reserved. 187