About the formation of C 60 fine particles with reprecipitation method in ethanol/carbon disulfide mixture

Abstract

We present a short communication to discuss some of the results of two works by Fujitstuka et al. [M. Fujitsuka, H. Kasai, A. Masuhara, S. Okada, H. Oikawa, H. Nakanishi, A. Watanabe, O. Ito, Chem. Lett. (1997) 1211; M. Fujitsuka, H. Kasai, A. Masuhara, S. Okada, H. Oikawa, H. Nakanishi, O. Ito, K. Yase, J. Photochem. Photobiol. A 133 (2000) 45] in which the photochemical and photophysical properties of a dispersion of fullerene fine particles are discussed. One of the simplest way to growth organic fine particles is the reprecipitation method. In this way microcrystals of fullerene molecules can be obtained with a good control on dimension and size distribution of the final aggregates. The existence and the distribution of fullerene clusters in these liquid solutions is usually attained and characterized by dynamic light scattering technique. In this short communication we want to address a common mistake derived from the widely used reprecipitation method. We show that photoncorrelation measurements from [M. Fujitsuka, H. Kasai, A. Masuhara, S. Okada, H. Oikawa, H. Nakanishi, A. Watanabe, O. Ito, Chem. Lett. (1997) 1211; M. Fujitsuka, H. Kasai, A. Masuhara, S. Okada, H. Oikawa, H. Nakanishi, O. Ito, K. Yase, J. Photochem. Photobiol. A 133 (2000) 45] are faulty due to the presence of a microemulsion between the two solvents used. In ethanol/carbon disulfide mixtures, CS 2 droplets dispersed in ethanol mimic in fact the existence of ≈ 300 nm clusters which, actually, do not exist.