Pressure-induced phenomena in single-walled carbon nanotubes probed by infrared spectroscopy

Abstract

The electronic properties of films of unoriented single-walled carbon nanotubes were studied by transmission measurements as a function of pressure. The energies of the optical transitions between the Van Hove singularities decrease with increasing pressure, which can be attributed to pressure-induced hybridization and symmetry-breaking effects. We observe an anomaly in the pressure-induced shift of the optical transitions at around 2 GPa due to a structural phase transition. The low-energy absorbance monotonically decreases with increasing pressure, suggesting an increasing carrier localization.

Keywords:

• infrared spectroscopy
• single-walled carbon nanotubes
• structural phase transition

Acknowledgements

We thank M. Kappes for fruitful discussions. We acknowledge the ANKA Ang-ström-quelle Karlsruhe for the provision of beamtime and thank B. Gasharova, Y.-L. Mathis, D. Moss, and M. Süpfle for assistance at the beamline ANKA-IR. Financial support by the Deutsche Forschungsgemeinschaft (KU 1432/3-1) is gratefully acknowledged.