Laser desorption mass spectroscopic study of fullerene coalescence and aggregation in reactive and non-reactive polymer films

Abstract

Laser-induced coalescence and aggregation/fragmentation of fullerenes in three newly available materials, namely, poly(N-vinylcarbazole) (PVK-C60/70), -C60/70 doped PVK(PVK/C60/70) and C60 doped polystyrene (PS/C60) films, were studied using time-of-flight mass spectrometry. Coalescence of fullerenes was found to be a little enhanced for PVK/C60/70 and greatly enhanced for PVK-C60/70, while no coalescence occurred for the non-reactive PS/C60. This was attributed to the presence of host-guest charge transfer interaction in the reactive host polymeric system which could produce reactive fullerenes, or that their fragments might be excited to triplet states with broken bonds forming "cage windows" which were sufficiently wide and had a sufficiently low barrier potential for other fullerene particles to enter and coalesce with them. The proposed role of charge transfer is supported by the correspondence between the intensity of coalescence and the level of photoconductivity of the materials studied. © 1997 Elsevier Science Ltd. All rights reserved.