Demonstrating the Metallic Nature of Single-Wall Carbon Nanotubes Using FT-Raman Spectroscopy

Photothermal emission from black substances is a well-known interference in FT-Raman spectroscopy when a relatively high power laser is used in the near infrared. This photothermal emission appears as a large, broad spectral feature in the 2800–3300 cm–1 region. We demonstrate that when KBr(s) is used as a matrix for measuring the Raman spectra of single-wall nanotubes (SWNTs), the photothermal emission disappears. We attribute this reduction to thermal transfer of energy from the SWNTs to the KBr. This demonstrates heat conduction, which is one of the characteristics of a metal. This is outlined as a three-hour laboratory for an upper-level science course that allows students to work with carbon-based nanostructures using a well-established technique.