Raman scattering and infrared absorption of the and isomers were studied at room temperature and 95 K. The results are compared to the response of pristine and doped According to the lower symmetry and the higher number of atoms exhibits much more vibrational modes than in particular at wave numbers above For lower energies the vibrational structure of resembles a downshifted and split spectrum. After the encapsulation of two scandium atoms the overall vibrational structure and the number of modes was preserved as a result of the similar geometric structure. From the very good correlation of the and cage modes metal to fullerene charge transfer induced shifts could be analyzed. The lines were found less shifted compared to the modes in exohedral doped (A=K,Rb,Cs). Increased line widths of low energy cage modes were attributed to an additional intramolecular relaxation channel related to the dynamics of the encapsulated scandium ions. A set of nine new lines with almost complementary Raman and infrared intensities was found for below 200, at 246 and at and attributed to vibrations. These vibrations were further identified as stretching and deformation modes. The valence force constant of 1.19 N/cm was derived with a linear three-mass oscillator model for Both, the charge transfer induced line shifts and the valence force constant indicate an effective transfer of approximately two electrons per scandium to the carbon cage. This is in agreement with an electronic state previously proposed on the basis of x-ray powder diffraction, x-ray photoemission spectroscopy (XPS), and quantum chemical calculations. The unexpected high number of vibrations is attributed to crystal field and factor group splitting.
Diatomic metal encapsulates in fullerene cages: A Raman and infrared analysis of and with symmetry
M. Krause, M. Hulman, H. Kuzmany, T. J. S. Dennis, M. Inakuma, H. Shinohara; Diatomic metal encapsulates in fullerene cages: A Raman and infrared analysis of and with symmetry. J. Chem. Phys. 1 November 1999; 111 (17): 7976–7984. https://doi.org/10.1063/1.480131
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