Résumé
We report the direct and unambiguous evidence of the existenceof inner semiconducting tube (iSCT) photoluminescence (PL)from measurements performed on four individual free-standingindex-identified double-walled carbon nanotubes (DWNTs).Based on thorough Rayleigh scattering, Raman scattering andPL experiments, we are able to demonstrate that the iSCT PLis observed with a quantum yield estimated as a few 10−6 independentlyof the semiconducting or metallic nature of theouter tube. This result is mainly attributed to ultrafast excitontransfer from inner to outer tube. Furthermore, by carryingout PL excitation experiments on the (14,1)@(15,12) DWNT,we show that the iSCT PL can be detected through the opticalexcitation of the outer tube (Fig. 1) indicating that the excitontransfer can also occur in the opposite way.