Nanosecond laser preparation of C-60 aqueous nanocolloids

Abstract

C-60 aqueous nanocolloids were prepared by irradiating a suspended aqueous solution of C-60 with intense nanosecond 532 and 355 nm laser pulses. The initial submicron crystal of C-60 was fragmented into nanoparticles, resulting in a transparent yellow solution which was followed by UV/vis absorption spectroscopy. The obtained absorption spectra were similar to those for C-60 bulk film and its nanoparticles, which have a size on the order of 10 nm, and their formation had thresholds with respect to laser fluence. The nanoparticles were confirmed by their SEM observation and by examining the centrifuging effect on the colloids, while possible photochemical decomposition was excluded by C-13 NMR analysis of 1,2-dichlorobenzene-d(4) solution, where the possible products can be dissolved in addition to C-60 nanoparticles. The present result is the first demonstration of the preparation of pure and very stable C-60 aqueous nanocolloids without any additives. The formation mechanism and potential application to biological testing and toxicity are discussed. (C) 2009 Elsevier B.V. All rights reserved.