  The Ajiki-Ando (A-A) splitting of single-walled carbon nanotubes(SWNT)
originating from the Aharanov-Bohm effect was observed in chiral specific SWNTs
by the magneto-absorption measurements conducted at magnetic fields of up to 78
T. The absorption spectra from each chirality showed clear A-A splitting of the
$E_{11}$ optical excitonic transitions. The parameters of both the dark-bright
exciton energy splitting and the rate of A-A splitting in a magnetic field were
determined for the first time from the well-resolved absorption spectra.
