Van Hove singularities and nonlinear photoluminescence in multiwalled carbon nanotubes

Abstract:

The absorption spectrum and photoluminescence spectrum of multiwalled carbon nanotubes (MWNTs) and the peaks related with Van Hove singularities (VHS) were obtained experimentally. Both the VHS formation and the change of band gaps in MWNTs depend on the intershell interaction. The VHS makes the probability of optical transitions enhanced, but the intershell interaction suppresses such radiative transitions. The excitation in the experiment involves a two-photon absorption process and the emission light has the effect of the optical frequency up-conversion.