Effect of Fullerene Encapsulation on Radial Vibrational Breathing-Mode Frequencies of Single-Wall Carbon Nanotubes

We investigate the effects of C₆₀ fullerene encapsulation on the radial breathing mode (RBM) of semiconducting single-wall carbon nanotubes (SWCNTs) under tunable laser excitations. The changes in the RBM frequencies after C₆₀ insertions show characteristic behavior; higher frequency shifts are observed in the case of smaller diameter tubes (dₜ1.32 nm) and lower frequency shifts, in the case of larger diameter tubes (dₜ1.32 nm). The observed frequency shifts are satisfactorily explained by the diameter-dependent interaction between the encapsulated C₆₀ and the host SWCNTs.