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

Abstract

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.

11 pages, 4 figures

References in corpus (4)

• The electronic properties of graphene
• Electron-electron interaction effects on optical excitations in semiconducting single-walled carbon nanotubes
• Cross-polarized optical absorption of single-walled nanotubes probed by polarized photoluminescence excitation spectroscopy
• Magnetic Brightening of Carbon Nanotube Photoluminescence through Symmetry Breaking

Cited by in corpus (3)

• Giant circular dichroism in individual carbon nanotubes induced by extrinsic chirality
• Direct Observation of Cross-Polarized Excitons in Aligned Single-Chirality Single-Wall Carbon Nanotubes
• Experimental determination of the local optical conductivity of a semiconducting carbon nanotube and its modification at individual defects