Giant Raman Response to the Encapsulation of Sulfur in Narrow Diameter Single-Walled Carbon Nanotubes

CHENGYIN FU; XIAOJUAN TIAN; BRYAN M. WONG; GUANGHUI LI; MINGGUANG CHEN; MIKHAIL E ITKIS; ROBERT C HADDON; MARÍA BELÉN OVIEDO; ELENA BEKYAROVA; JUCHEN GUO

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2016

0002-7863

Encapsulation of sulfur in HiPCO-SWNTs leads to large changes in the Raman spectra with the appearance of new peaks at 319, 395, and 715 cm?1 which originate from the sulfur species within the SWNTs, while the high frequency SWNT bands (ν > 1200 cm?1) are decreased in intensity. The encapsulated species also shifts the near-IR interband electronic transitions to lower energy by more than 10%. These effects seem to originate with the van der Waals interaction of the confined sulfur species with the walls of the SWNTs which are not expected to be significant in the case of the previously studied large diameter SWNTs. We suggest that sulfur in the small diameter SWNTs exists as a helical polymeric sulfur chain that enters the SWNT interior in the form of S2(3Σg?) molecules which undergo polymerization to linear diradicals.