Optical properties of copper naphthalocyanine nanoparticles prepared by laser ablation in liquid

Copper naphthalocyanine nanoparticles were successfully prepared by laser ablation in liquid. Micron-size copper naphthalocyanine powders were used as the raw material in water and were irradiated with a laser beam (Nd:YAG, SHG) to obtain nanoparticles. Nanoparticles were examined by scanning electron microscopy, dynamic light scattering, a spectrophotometer, and Raman spectroscopy. Even in the case of irradiation at low laser fluence and for short irradiation times, nanoparticles were obtained owing to the comparatively low threshold of laser ablation. Laser irradiation changed the crystal structure, but the composition of the nanoparticles was not altered by laser irradiation. The dispersion stability of nanoparticle solution was very high, and absorbance of the solution was almost constant without precipitation. The conversion rate from raw material to nanoparticle was 85.5%. The Gruneisen coefficient for the copper naphthalocyanine nanoparticles was also high; therefore, the produced copper naphthalocyanine nanoparticles were suitable as a contrast agent for photoacoustic imaging.