On the structure and normal modes of hydrogenated Ti-fullerene compounds
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When titanium covers a C60 core, the metal atoms may suppress the fullerene's capacity of storing hydrogen, depending on the number of Ti atoms covering the C60 framework, the Ti–C binding energy, and diffusion barriers. In this article, we study the structural and vibrational properties of the C60TiH n (n = 2, 4, 6, and 8) and C60Ti6H48 compounds. The IR spectra of C60TiH n compounds have a maximum attributable to the Ti–H stretching mode, which shifts to lower values in the structures with n = 4, 8, while their Raman spectra show two peaks corresponding to the stretching modes of H2 molecules at apical and azimuthal positions. On the other hand, the IR spectrum of C60Ti6H48 shows an intense peak due to the Ti–H in-phase stretching mode, while its Raman spectrum has a maximum attributed to the pentagonal pinch of the C60 core. Finally, we have found that the presence of one apical H2 molecule enhances the pentagonal pinch mode, becoming the maximum in the Raman spectrum.
KeywordsRaman Hydrogen storage Coated fullerene Transition metals Infrared Atomic clusters
The authors acknowledge al Departamento de Supercómputo DGSCA-UNAM for the support provided.
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