Vibrational Properties of Interacting Linear Carbon Chains Inside Carbon Nanotubes

Graduate #83
Discipline: Physics
Subcategory: Nanoscience

Ross Siegel - Rensselaer Polytechnic Institute
Co-Author(s): Aldo Raeliarijaona, University of Nebraska, Lincoln, NE. Jorge Alarcon, Unknown Current Affiliation/Location. Humberto Terrones, Rensselaer Polytechnic Institute, Troy, NY.

---

Encapsulated linear carbon chains inside carbon nanotubes have come about spontaneously. Throughout these works it has been assumed that the chains and tubes are non interacting, except by Van der Waals forces [1,2,3]. Linear chains interacting with the tube via sp3 bonding should not be excluded from possibility. The Vibrational modes and Raman activity of this novel system are investigated using the plane wave density functional theory package, Quantum Espresso, with a norm conserving pseudopotential. Armchair and zigzag carbon nanotubes with diameters closest to the length of CxH2 in vacuum were paired for these calculations to minimize strain. Chains of carbon were placed radially across the nanotubes and, while maintaining the cylindrical shape of the tube, were relaxed until the forces reached sufficient minima.
Preliminary results show the Raman active modes soften due to strain in the chain. The linear chains of C4H2, C6H2, and C10H2 in vacuum were compared to C4 in a 5-5 CNT, C6 in a 7-7 CNT, and C10 in a 10-10 CNT, respectively. With respective softenings of 97cm-1, 117 cm-1, and 149 cm-1. Raman activity of larger chains will be studied as well as other systems of interacting linear chains inside carbon nanotubes.

1) Xinlou Zhao et al. PRL; May, 2003. Vol 90, #18; 90.187401.

2) N.F. Andrade et al. Carbon; 2015. Vol 90, pg 172-180.

3) Lei Shi et al. Nature Materials. April, 2016. DOI:10.1038/NMAT4617

Ross Siegel, Vibrational Properties of Intera.docx

Funder Acknowledgement(s): NSF EFRI - 143311

Faculty Advisor: Humberto Terrones, terroh@rpi.edu

Role: I generated the structures, developed the method through the use of Quantum Espresso, and identified the vibrational modes of interest.