Separation of SWNTs by diffusion

Here we report on an adapted diffusion method by which we managed to separa te the starting material of single-wall carbon nanotubes (SWNTs) into three different fractions. The method is based in the migration of charged speci es dispersed in buffer in response to an electric field. All three isolated fractions were characterised by Raman spectroscopy (lambda = 647.1 nm). Th e Raman spectra of the first two fractions and the starting material differ slightly from one another in both energy-spectral regions. This suggests t hat during migration in the electric field the SWNTs were distributed by th eir diameter and possibly by length.