UV-vis spectroscopic properties of nC60 produced via extended mixing.

Colloidally stable C(60) suspensions produced via extended mixing in water (aq/nC(60)) are highly heterogeneous with respect to particle size and morphology. Ultraviolet-visible (UV-vis) absorption spectra of aq/nC(60) are often used as a supplemental tool to dynamic light scattering (DLS), transmission electron microscopy (TEM), and other analytical methods to characterize aq/nC(60). In the present study, the UV-vis spectra provide information about the average particle size and the interactions between C(60) and water. We report that the decrease in relative absorption in the 240-290 nm range is a function of magnetic stirring time, that the average size (Z(ave)) of an aq/nC(60) suspension determines the position of absorbance maximum of its 360 nm band, and that the methods used to prepare and fractionate nC(60) affect the extent of the blue shift in this band that occurs due to a decrease in Z(ave). We also confirm that the broad absorption band in the 400-600 nm region is a result of C(60) aggregation.