Tailoring nanoparticles of aromatic and dye molecules by excimer laser irradiation

Nanosecond 351 nm excimer laser irradiation of microcrystalline powders of aromatic hydrocarbons and phthalocyanine (Pc) dyes in water results in conversion from opaque suspensions to transparent colloidal solutions. Formation of 100 nmsized particles are successfully con®rmed for oxo(phthalocyaninato)vanadium(IV) (VOPc) by AFM observation. The particles in solution are stable, while some Pc colloid solutions show interesting slow UV absorption spectral changes, which is interpreted in terms of phase transition. It is discussed that the present laser ablation of solution is regarded not only as a new nanoparticle formation method but also as a control way of molecular aggregation in nanoparticles. # 2000 Elsevier Science B.V. All rights reserved