The multibody effects in the optical spectra of single-walled carbon nanotubes (SWCNT) and other carbon nanostructures are investigated using resonant Raman spectroscopy. Resonance enhancement of the Raman scattering intensity of the radial breathing mode in SWCNTs is used as a probe of tube chirality and of one-dimensional electronic structure. The confocal magneto-Raman microscope at NIST permits continuously tunable laser excitation from the near-infrared to the ultraviolet. This novel Raman facility consists of a microscope capable of working over a wide range of temperatures (T = 4.2-300 K) and magnetic fields (H = 0-8 T) coupled to a triple grating spectrometer with ultimate Raleigh rejection capabilities, thereby permitting low-frequency or Terahertz Raman spectroscopy. As a member of a multidisciplinary NIST team focused on nanometrology of carbon nanostructures, we obtain measures of sample characteristics of value to academic, industrial and nano-environmental, -health, and -safety (Nano EHS) communities such as sample quality, purity, alignment, and physical features (e.g. diameter and length). Nanotube samples of unprecedented purity are available and permit the study of fundamental physical properties. Characterization of bulk, single, DNA-wrapped, suspended, and nanoparticle-functionalized SWCNT samples are all of interest to the program. The unique optical properties of complementary materials such as graphene are also critical components of our research. A large, NIST-wide program in graphene measurement science is underway to explore the underlying physics of this novel material. It involves the combination of Raman, STM, and quantum Hall effect measurements, with device fabrication and substrates of, but not limited to, SiC and SiO₂.

 

key words

Carbon nanotube; Exciton; Graphene; Magnetic field; Nanotechnology; Photoluminescence; Raman microscope; Resonance Raman; Temperature dependence;

Citizenship:  Open to U.S. citizens

Level:  Open to Postdoctoral applicants