Study of Short-Pulse-Induced Solute Migration in the Presence of Convection
Po-Yuan Huang1*, Yu-Ting Kuo1, Yi-Ci Li1, Tai-Huei Wei1
1Department of Physics, National Chung Cheng University, Chiayi, Taiwan
* presenting author:Po-Yuan Huang,
Using the Z-scan technique with 532 nm 19 ps laser pulses separated by various times τp-p = n*0.1 s (n being any positive integers) covering the mass diffusion time (τmd = 0.3 s), we have verified that the outward solute migration of chloro-aluminum phthalocyanine (ClAlPc) dissolved in ethanol can be induced with the pulse energy exceeding a threshold εt. By additionally applying a temperature gradient in this sample, either parallel or anti-parallel to the light propagation direction, we re-conduct the same measurements and find that εt increases. This indicates that the outward solute migration is weakening. We attribute this migration weakening to the temperature-gradient-driven convection.

Keywords: solute migration, convection, Z-scan