Optical Properties of Cu, Ni, and Co Nanoparticles Synthesized by Pulsed Laser in Liquid Ambient

In this paper, we report an experimental-theoretical study on the optical properties of copper (Cu), nickel (Ni), and cobalt (Co) nanoparticles synthesized by pulsed laser ablation (PLAL) in deionized water, acetone, and ethanol. Using Mie theory, the theoretical calculation of the extinction, absorbance, scattering cross-sections, and the radial dependence of the electric field inside the metallic nanoparticles (MNPs) was carried out. The MNPs were synthesized using a Nd:YAG (Spectra Physics Indi 10) laser and, the characterization of the samples was carried out by ultraviolet and visible spectroscopy (UV–vis) and scanning electron microscopy (SEM). UV–vis spectroscopy allowed corroborating the theoretical calculations obtained from the Mie theory, where it was possible to determine the relationship between shape and size of the MNPs, with surface plasmon resonance band position. Experimentally, Cu MNPs synthesized in deionized water showed three bands located around ⁓ 240 nm, ⁓ 280 nm, and ⁓ 350 nm, which after 48 h, no significant shift in the bands was observed. Likewise, for the Ni MNPs synthesized in deionized water (absorbance between 200 and 250 nm), no significant shift was observed. On the other hand, for Co MNPs were identified two bands located around 235 and 280 nm, which were not present right after synthesis. For all samples synthesized in acetone, the absorbance band was observed around 330 nm with a more notable broadening for Cu than for Ni and Co, indicating a larger average particle size for Cu. In addition, all samples synthetized in ethanol presented two absorbance peaks between 225 and 256 nm, and only for Cu, an additional peak around 590 nm was observed. After 2 months, the samples still showed stability. SEM images showed spherical nanoparticles with an average size of 33 nm, 58 nm, and 51 nm for Cu, Ni, and Co, respectively.