On the evaporation kinetics of [60] fullerene in aromatic organic solvents.

We investigate the effect of C60 fullerene nanospheres on the evaporation kinetics of a number of aromatic solvents with different levels of molecular association, namely, benzene, toluene, and chlorobenzene. The dependence of the evaporation rate on the fullerene concentration is not monotonic but rather exhibits maxima and minima. The results strongly support the notion of molecular structuring within the liquid solvent controlled by the nature of the fullerene/solvent interaction and the level of molecular association within the solvent itself.

On the development of a confocal Rayleigh-Brillouin microscope.

This Note illustrates how a confocal microscope may be modified to conduct Rayleigh-Brillouin mapping experiments that yield very useful information on the mechanical properties of interfacial materials in small volume elements. While the modifications to the microscope are quite straightforward, they do entail significant changes in the optical design. The instrument described herein consists of an argon ion laser equipped with an actively stabilized intercavity etalon that serves as the excitation source for a modified Zeiss LSM 310 confocal laser scan microscope. The optics of the microscope were reconfigured to enable interfacing of the microscope with a tandem triple-pass Fabry-Perot interferometer. This instrument enables three-dimensional Rayleigh-Brillouin spectral mapping of samples at micron spatial resolution. The performance of the instrument and its ability to perform both lateral and depth scans of the acoustic phonon velocity and, hence, the longitudinal modulus across bonded polymer/polymer and polymer/ceramic interfaces are illustrated and discussed.

Study of the hydrostatic pressure dependence of the Raman spectrum of single-walled carbon nanotubes and nanospheres.

We have investigated the behavior of single-walled carbon nanotubes and nanospheres (C(60)) under high hydrostatic pressure using Raman spectroscopy over the pressure range 0.2-10 GPa using a diamond anvil cell. Different liquid mixtures were used as pressure transmission fluids (PTF). Comparing the pressure dependence of the Raman peak positions for the nanotubes and the nanospheres in different PTF leads to the observation of a number of new phenomena. The observed shift in Raman peak position of both radial and tangential modes as a function of applied pressure and their dependence on the PTF chemical composition can be rationalized in terms of adsorption of molecular species from the of PTF on to the surface of the carbon nanotubes and/or nanospheres. The peak shifts are fully reversible and take place at a comparatively modest pressure (2-3 GPa) that is far below pressures that might be required to collapse the nanoparticles. Surface adsorption of molecular species on the nanotube or nanospheres provides a far more plausible rational for the observed phenomena than ideas based on the notion of tube collapse that have been put forward in the recent literature.