           AnneMarie Dowgiallo, Kevin S. Mistry, Justin C. Johnson, Obadiah G. Reid,^ ‡ and Jeffrey L. Blackburn  !! "# $ % Transient absorption spectra for neat SWCNT and SWCNTC 60 bilayer films at long delay times (~300 ps) after selective excitation of the nanotubes (a, d) and C 60 (b, e). (6,5) and (7,5) SWCNT films were excited using 1000 and 1050 nm pump pulses, respectively, corresponding to their S 11 transitions. Regardless of pump wavelength, a longlived S 11 bleach is present, as well as an IA at 1174 and 1230 nm corresponding to the trion transition, X + , for the (6,5) and (7,5) SWCNT bilayer films, respectively. Panels c and f show the integrated time slices at 1174 nm and 1230 nm for (6,5) and (7,5) SWCNT bilayer films, respectively, following both nanotube and C 60 excitation. The thickness of each layer for both nanotube chiralities was ~10 nm SWCNT and ~70 nm C 60 . In all cases, the pump fluence was ~3 x10 12 photons pulse 1 cm 2 and excitation was through the nanotube layer first (backside).