Formation and characteristics of Cu colloids from CuO powder by laser irradiation in 2-propanol

The laser ablation technique has been employed to prepare Cu colloids from CuO powder in 2-propanol using wavelengths of 1064 and 532 nm. The copper colloids resulting from 1064 nm irradiation were conspicuously stable under aerobic conditions without any protective agent present. In addition to Cu particles, the formation of oxidized product, acetone, from 2-propanol was detected by gas chromatography. The discrepancy in the Cu colloidal formation between 1064 and 532 nm was analyzed on the basis of the absorptive ability of CuO powder, the results of the power dependence, and the measurements of the dose effect. The process of photoinduced coalescence that formed larger spherical particles was found to be wavelength-dependent. The stability of the Cu colloids could be the result of their near-perfect spherical shape and the effect of their larger size.