Fingerprinting Seamless Single-Walled Carbon Nanotube Junctions via Migration of Encapsulated N 2 Molecules From bottom to top , are arrays of vertically aligned SWNT continuous ?

Structure control such as diameter changes along single-walled carbon nanotubes (SWNTs) can be achieved in arrays of vertically aligned (VA-) SWNTs by switching the feedstock during growth. The local nature of the macroscopic transition from one diameter to another is then questioned as one can either envisage seamless transitions or discontinuous individual SWNTs. Here, we demonstrate that encapsulated molecules can serve as markers to doubtlessly identify seamless interconnections in macroscopic samples. A migration of nitrogen molecules inside continuous SWNTs is observed by bulk scale measurements on double-layered SWNT array synthesized from different carbon/nitrogen feedstocks. The existence of N2 molecules at the top of the SWNT array proves continuous SWNTs throughout double layered arrays with different diameters.