Cloaking by π-electrons in the infrared

• Published in: Physica Status Solidi. B: Basic Solid State Physics Vol. 253; no. 12; pp. 2457 - 2460
• Main Authors: Pekker, Áron, Németh, Gergely, Botos, Ákos, Tóháti, Hajnalka M., Borondics, Ferenc, Osváth, Zoltán, Biró, László P., Walker, Kate, Khlobystov, Andrei N., Kamarás, Katalin
• Format: Journal Article
• Language: English
• Published: Blackwell Publishing Ltd 01-12-2016
• Subjects: carbon nanotubes; Cloaking; dielectric screening; Graphene; Hybrid systems; infrared; Infrared radiation; Infrared spectroscopy; Metamaterials; Nanostructure; Single wall carbon nanotubes; Vibration
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.201600399

Hybrid materials composed of single walled carbon nanotubes (SWCNTs) as hollow containers and small molecules as fillers possess intriguing physical and chemical properties. Infrared spectroscopy is a useful method in most cases to characterize hybrid systems; however, regardless of the type of small molecule encapsulated in the SWCNT, the IR spectrum of the hybrid system remains silent. The possible explanation involves the highly polarizable π‐electron system of the SWCNTs. Image charges induced in the SWCNT walls cancel out the transition dipole moment of the molecular vibrations resulting in the cloaking of the material inside the nanotube. To confirm the role of the delocalized π‐electron system in this process, insulating boron nitride nanotubes filled with C60 were also investigated and found to be transparent to infrared radiation. We have also demonstrated the cloaking effect in two dimensions using a thin film of C60 covered by single layer graphene. The significance of our results lies in the fact that the cloaking layer is a real material, not a metamaterial.