Speaker
Prof.
Mohammad Hossein Mahdieh
(Department of Physics, Iran University of Science and Technology, Narmak, 16846-13114, Tehran, Iran)
Description
In this paper, laser induced optical breakdown in colloidal nanoparticles and in the presence of an applied electric field is studied by using pump probe beam technique. Colloidal nanoparticles of Ag (as a good conductor), Al$_2$O$_3$ and TiO$_2$ (with good dielectric properties) were used in this investigation. We have shown recently that an external electric field can influence the generated nanoparticles by laser ablation in liquid atmosphere. In the experiments, the optical breakdown was induced by an Nd:YAG laser beam (operating at 1064 nm with pulse duration ∼30 ns). Applying an electric field (at the order of several 10 V) perpendicular to the laser beam direction can influence the breakdown plasma condition. Using an optical splitter, a small portion of the breakdown beam was taken and used as probe beam. The time varying transversely transmission of the probe beam through the plasma was measured during the breakdown process. According to the results, the nanoparticles characteristics, laser pumping beam intensity, and the applied electric field have significant influence in the breakdown process. Our results also show different dynamic behaviors for conductor and dielectric nanoparticles at different interaction conditions including the electric field effects. The results are useful for nanoparticle synthesis by laser ablation in distilled water in in the presence of external field. In such conditions the optical breakdown intensity threshold of ambient water can influenced by generated nanoparticles during the synthesis process when an electric filed is also applied.
Primary author
Prof.
Mohammad Hossein Mahdieh
(Department of Physics, Iran University of Science and Technology, Narmak, 16846-13114, Tehran, Iran)
Co-author
Dr
Marzieh Akbari Jafarabadi
(Department of Physics, Iran University of Science and Technology, Narmak, 16846-13114, Tehran, Iran)
