Raman scattering in C60 and alkali-metal-doped C60 films

Intermolecular Interaction between Single-Walled Carbon Nanotubes and Encapsulated Molecules Studied by Polarization Resonance Raman Microscopy

In the present study, we investigated the intermolecular interactions between single-walled carbon nanotubes (SWCNTs) and encapsulated molecules by polarization resonance Raman microscopy. C₇₀ encapsulated in SWCNTs is investigated under incident laser polarization parallel and perpendicular to the tube axis. We employed two excitation laser wavelengths 442 and 532 nm, which are in resonance with different electronic states of C₇₀. Under 532 nm excitation, no distinct polarization dependence is found in the Raman spectral pattern, while under 442 nm excitation, a peak not previously seen for this excitation wavelength was clearly observed for parallel excitation. This result can be explained by the modulation of the resonance Raman process via a charge transfer contribution between C₇₀ and the SWCNTs, which is sensitive to the incident polarization as well as the excitation wavelength. The intensity of the local electronic field inside a SWCNT is higher for the parallel excitation than the perpendicular excitation when the nanotubes are in a bundle. The results can be explained by field localization effects at the nanotube walls, qualitatively supported by finite-difference time-domain simulations.

Synthesis and high pressure studies of white luminescence host-guest complex nanocrystals based on C60 and p-But-calix[8]arene

Host-guest structured nanocrystals consisting of p-But-calix[8]arene and fullerene C₆₀ were fabricated with the facial solution deposition method. The as-prepared host-guest complex nanocrystals are well crystallized in a tetragonal structure, in which the guest C₆₀ and host p-But-calix[8]arene molecules interact with each other via the van der Waals force. The host-guest crystal has a wider band gap compared to that of C₆₀ crystals. The luminescence range of the host-guest structured nanocrystals was widely extended, and its photoluminescence (PL) intensity was highly enhanced by one order of magnitude. High pressure studies on such host-guest nanocrystals were carried out using the diamond anvil cell technique with the associated spectroscopic measurements. Raman and PL spectra show a phase transition occurred on the samples owing to the deformation of fullerene molecules. A PL behavior change was also observed synchronously with the phase transition. The host-guest structure strongly influences the structure and optical behaviors of C₆₀ under pressure.

Catalysis to discriminate single atoms from subnanometric ruthenium particles in ultra-high loading catalysts

We report a procedure for preparing ultra-high metal loading (10–50% w/w Ru) Ru@C₆₀ nanostructured catalysts comprising exclusively Ru single atoms or mixtures of single atoms and clusters.