Heat-induced transformations in coronene—single-walled carbon nanotube systems

Coronene molecules are used as filler for single-walled carbon nanotubes. Variation of the synthesis temperature regimes leads to formation of different types of carbon nanostructures inside the nanotubes. Accurate determination of the structures by optical spectroscopy methods remains an important issue in composite materials. Clear distinction between adsorbed organic molecules on the surface of the tubes and filled structures may be accessed by Raman and photoluminescence spectroscopies. We perform additional heat treatment after the initial synthesis procedure and show the evolution of the optical spectral features corresponding to the filled structures and adsorbed materials on the surface of single-walled carbon nanotubes. © 2015 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI: 10.1117/1.JNP.10.012504] Keywords: graphene nanoribbons; coronene molecules; coronene stacks; columns; singlewalled carbon nanotubes; nanoreactor. Paper 15069SS received Jul. 28, 2015; accepted for publication Sep. 4, 2015; published online Nov. 5, 2015. 1 Introduction Single-walled carbon nanotubes (SWCNTs) can be used as a reactor for the synthesis of nanostructured materials.1 Nanotubes serve as a template and govern the geometry of encapsulated aggregates.2 Changing the properties of the nanotubes leads to extra control over the inner structures.3 Despite the fact that inner molecules become concealed by the surface of the nanotubes, Raman spectroscopy and photoluminescence (PL) spectroscopy are convenient tools for their detection and study. For example, encapsulated dye molecules demonstrate significant Raman scattering response and PL light emission.4,5 Coronene molecules are polycyclic aromatic hydrocarbons which can be used as filler for SWCNTs with diameters starting at around 1.2 nm.3,6,7 Depending on nanotube diameter, the filling rate, and heat treatment coronene molecules can form stacks inside or can be polymerized into hydrogen-terminated...