Metallocenes inside single-walled carbon nanotubes (SWCNTs) are very promising topic of research. The filled SWCNTs can find applications in nanoelectronics, construction materials, spintronics, magnetic storage devices, magnetic recording devices, solar cells and light emission. Starting the first study [1], metallocenes were incorporated inside SWCNTs using different techniques with gas, liquid phase [2,3]. The gas phase includes the evaporation of metallocene with carbon nanotubes. The liquid phase filling includes dissolving the metallocene in organic solvents and mixing with carbon nanotubes [4]. There are many stages of filling with multi-step cleaning and separations. The filled SWCNTs are investigated with Raman spectroscopy, optical absorption spectroscopy, near edge X-ray absorption fine structure spectroscopy, and photoemission spectroscopy [5,6].

[1] Guan L.H., Shi Z.J., Li M.X., Gu Z.N. Ferrocene-filled single-walled carbon nanotubes. Carbon. 2005. V.43. N.13. P.2780-2785.

[2] Li L.J., Khlobystov A.N., Wiltshire J.G., Briggs G.A.D., Nicholas R.J. Diameter-selective encapsulation of metallocenes in single-walled carbon nanotubes. Nature Materials. 2005. V.4. N.6. P.481-485.

[3] Liu X.J., Kuzmany H., Saito T., Pichler T. Temperature dependence of inner tube growth from ferrocene-filled single-walled carbon nanotubes. Physica Status Solidi B-Basic Solid State Physics. 2011. V.248. N.11. P.2492-2495.

[4] Shiozawa H., Giusca C.E., Silva S.R.P., Kataura H., Pichler T. Capillary filling of single-walled carbon nanotubes with ferrocene in an organic solvent. Physica Status Solidi B-Basic Solid State Physics. 2008. V.245. N.10. P.1983-1985.

[5] Plank W., Pfeiffer R., Schaman C., Kuzmany H., Calvaresi M., Zerbetto F., Meyer J. Electronic Structure of Carbon Nanotubes with Ultrahigh Curvature. ACS Nano. 2010. V.4. N.8. P.4515-4522.

[6] Kharlamova M.V., Kramberger C., Saito T., Sato Y., Suenaga K., Pichler T., Shiozawa H. Chirality-dependent growth of single-wall carbon nanotubes as revealed inside nano-test tubes. Nanoscale. 2017. V.9. N.23. P.7998-8006.