Nanosecond 351 nm excimer laser irradiation of microcrystalline powders of
aromatic hydrocarbons and phthalocyanine (Pc) dyes in water results in conv
ersion from opaque suspensions to transparent colloidal solutions. Formatio
n of similar to 100 nm-sized particles an successfully confirmed for oxo(ph
thalocyaninato)vanadium(IV) (VOPc) by AFM observation. The particles in sol
ution are stable, while some Pc colloid solutions show interesting slow UV
absorption spectral changes, which is interpreted in terms of phase transit
ion. It is discussed that the present laser ablation of solution is regarde
d not only as a new nanoparticle formation method but also as a control way
of molecular aggregation in nanoparticles. (C) 2000 Elsevier Science B.V.
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