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SURFACE-ENHANCED RAMAN SCATTERING, PHOTOLUMINESCENCE AND VISCOSITY STUDIES ON C60 AGGREGATES IN N-METHYL-2-PYRROLIDINONE

I. Baltog1,* , L. Mihut1, M. Baibarac1, N. Preda1, T. Velula1, S. Lefrant2

Affiliation

  1. National Institute of Materials, Lab. of Optics and Spectroscopy, P. O. Box MG-7, RO-77125, Bucharest, Romania
  2. Institut de Materiaux de Nantes, Laboratoire de Physique Cristalline, 2 Rue de la Houssiniere, B.P. 32229, 44322 Nantes, France

Abstract

Correlated studies of Surface Enhanced Raman Scattering (SERS) spectroscopy, photoluminescence (PL) and viscosity on aggregation of C60 fullerene in N-methyl-2 pyrrolidinone (NMP) solutions were performed. The aggregation is a result of storing of the solutions at the room temperature for different periods of time. The modified phonon spectrum in the aggregate phase is a consequence of the intermolecular interactions that lead to a large reduction in parent Ih C60 symmetry. The Raman range below 800 cm-1 is the most diagnostic for aggregate assignment. Substitution of the original of Hg (1) band from ~269 cm-1 with a new one at ~255 cm-1 relates the formation of (C60, NMP) complexes. In the second stage of aggregation, this band shifts at ~246 cm-1 and a new band, associate to the interball interaction, is formed at ~94 cm-1. PL emission of the C60 solutes in NMP presents two components, one in red (1.92-2.00 eV) and another in green (2.18-2.3 eV), which originate in two successive processes. Their weights depend on C60 concentration and on storage time. In the beginning are formed quickly molecular complexes (C60, NMP) by charge transfer, which on associate slowly in stable aggregates. A dependence of specific viscosity on C60 solution concentration is observed too..

Keywords

Fullerenes, Aggregation, Surface Enhanced Raman Scattering, Photoluminescence, Viscosity, N-methyl-2-pyrrolidinone.

Submitted at: July 4, 2005
Accepted at: July 21, 2005

Citation

I. Baltog, L. Mihut, M. Baibarac, N. Preda, T. Velula, S. Lefrant, SURFACE-ENHANCED RAMAN SCATTERING, PHOTOLUMINESCENCE AND VISCOSITY STUDIES ON C60 AGGREGATES IN N-METHYL-2-PYRROLIDINONE, Journal of Optoelectronics and Advanced Materials Vol. 7, Iss. 4, pp. 2165-2172 (2005)