Controlled isotope arrangement in 13C enriched carbon nanotubes

We report the synthesis of a novel isotope engineered ^13 C–^12 C heteronuclear nanostructure: single-wall carbon nanotubes made of ^13 C enriched clusters which are embedded in natural carbon regions. The material is synthesized with a high temperature annealing from ^13 C enriched benzene and natural C_60, which are co-encapsulated inside host SWCNTs in an alternating fashion. The Raman 2D line indicates that the ^13 C isotopes are not distributed uniformly in the inner tubes. A semi-empirical method based modeling of the Raman modes under ^13 C isotope enrichment shows that experimental data is compatible with the presence of ^13 C rich clusters which are embedded in a natural carbon containing matrix. This material may find applications in quantum information processing and storage using nuclear spins as qubits.