In Section 2.3, we explored the possibility of evaluating thermophoresis using MSD. However, as previously mentioned, the evaluation of thermophoresis using MSD heavily depends on the initial position and distribution of the PSNPs. In experiments, it is crucial to perform single particle tracking under conditions where the particle concentration is sufficiently low when using MSD for evaluation. In actuality, we tried to measure the MSD of PSNPs under laser irradiation at dilute concentrations, but the data showed significant variability due to dependence on the initial positions, preventing us from obtaining systematic results. Therefore, in the following experiments, we will observe thermophoresis at a moderate particle concentration and discuss the steady-state spatial distribution using time-averaged data.