We report on the first tunable resonant Raman scattering study performed on suspended isolated and coupled single-wall carbon nanotubes, unambiguously identified by electron diffraction. Besides the confirmation of the relation between the structural properties, the radial breathing frequency and the optical resonances for isolated metallic nanotubes, we evidence that interacting nanotubes experience drastic modifications of their resonance fingerprints. We first demonstrate a degeneracy lifting of an electronic level in a bundle of identical zigzag nanotubes. We then show the existence of a strong energy transfer mediated by a mechanical coupling between two nonidentical bundled nanotubes.

When a rotating rod is brought into a polymer melt or concentrated polymer solution, the meniscus climbs the rod. This spectacular rod climbing is due to the normal stresses present in the polymer fluid and is thus a purely non-Newtonian effect. A similar rod climbing of an interface between two fluids has therefore been taken as a signature that one of the fluids exhibits normal stress effects. We show here, however, that the effect can occur with simple Newtonian fluids: it occurs when a Taylor-Couette instability happens in the less viscous of the two liquids but not in the more viscous one.