Anisotropic polarizability of isolated semiconducting single-wall carbon nanotubes in alternating electric fields

We measure the linear dichroism for aqueous suspensions of isolated semiconducting single-wall carbon nanotubes (SWCNTs) in alternating electric fields. The field-induced alignment of length-purified SWCNTs is determined from the anisotropy of the first and second interband optical transitions for the (6,5) semiconducting species. At 3 kHz, the effective anisotropic polarizability of the DNA-wrapped SWCNTs is of order 10(-28) F m(2), comparable to that of a high-aspect-ratio conducting rod, but a factor of 5 larger than that of gold colloidal rods and an order of magnitude larger than that of tobacco mosaic virus. (C) 2007 American Institute of Physics.