Electron-Hole Asymmetry in Single-Walled Carbon Nanotubes Probed by Direct Observation of Transverse Quasi-Dark Excitons

Autor:	Miyauchi, Yuhei, Ajiki, Hiroshi, Maruyama, Shigeo
Rok vydání:	2009
Předmět:	Condensed Matter - Materials Science
Druh dokumentu:	Working Paper
DOI:	10.1103/PhysRevB.81.121415
Popis:	We studied the asymmetry between valence and conduction bands in single-walled carbon nanotubes (SWNTs) through the direct observation of spin-singlet transverse dark excitons using polarized photoluminescence excitation spectroscopy. The intrinsic electron-hole (e-h) asymmetry lifts the degeneracy of the transverse exciton wavefunctions at two equivalent K and K' valleys in momentum space, which gives finite oscillator strength to transverse dark exciton states. Chirality-dependent spectral weight transfer to transverse dark states was clearly observed, indicating that the degree of the e-h asymmetry depends on the specific nanotube structure. Based on comparison between theoretical and experimental results, we evaluated the band asymmetry parameters in graphene and various carbon nanotube structures. Comment: 11 pages, 4 figures
Databáze:	arXiv
Externí odkaz:	http://arxiv.org/abs/0910.3195 Zobrazit plný text záznamu View this record from Arxiv