Time-resolved photoemission was used to differentiate between excitons and free carriers in non-fluorescing bundles of single walled carbon nanotubes (SWNT). Present findings show that direct interband excitations in semiconductive SWNTs lead to the formation of strongly bound excitons, indicating that proximity effects in SWNTs bundles do not destroy a one-dimensional character of optical excitations. (c) 2007 Published by Elsevier B.V.