Ultrafast Exciton Hopping Observed in Bare Semiconducting Carbon

Letter pubs.acs.org/JPCL

Ultrafast Exciton Hopping Observed in Bare Semiconducting Carbon Nanotube Thin Films with Two-Dimensional White-Light Spectroscopy Randy D. Mehlenbacher,† Jialiang Wang,‡ Nicholas M. Kearns,† Matthew J. Shea,‡ Jessica T. Flach,†,§ Thomas J. McDonough,†,§ Meng-Yin Wu,∥ Michael S. Arnold,*,‡ and Martin T. Zanni*,† †

Department of Chemistry, University of WisconsinMadison, 1101 University Avenue, Madison, Wisconsin 53703, United States Department of Materials Science and Engineering, University of Wisconsin−Madison, 1509 University Avenue, Madison, Wisconsin 53706, United States ∥ Department of Electrical and Computer Engineering, University of WisconsinMadison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States ‡

S Supporting Information *

ABSTRACT: We observe ultrafast energy transfer between bare carbon nanotubes in a thin film using two-dimensional (2D) white-light spectroscopy. Using aqueous two-phase separation, semiconducting carbon nanotubes are purified from their metallic counterparts and condensed into a 10 nm thin film with no residual surfactant. Cross peak intensities put the time scale for energy transfer at