研究目的
Investigating the effect of laser heating on the diffusion of core-shell colloids with plasmonic gold nanoparticle cores and thermoresponsive hydrogel shells, and the transition from normal diffusion to superdiffusion under photothermal heating conditions.
研究成果
The study demonstrates that photothermal heating of plasmonic core-shell microgels induces a transition from normal diffusion to superdiffusion, with significant deswelling of the hydrogel shells. The effective temperature increase in the scattering volume can reach almost 10 K, leading to a pronounced change in the hydrodynamic radius of the microgels. Angle-dependent dynamic light scattering is crucial for understanding the diffusion behavior under photothermal heating conditions.
研究不足
The study is limited by the assumption of normal diffusion in the high-q limit for estimating temperature increases and the need for careful alignment of the pump and probe lasers. The effects of photon pressure and potential local heating effects near the nanoparticles were not fully explored.
1：Experimental Design and Method Selection:
Angle-dependent pump-probe dynamic light scattering was used to study the motion of core-shell colloids during laser heating. The method involves recording intensity-time autocorrelation functions while illuminating the samples with a pump laser to heat the gold cores.
2：Sample Selection and Data Sources:
Core-shell colloids with gold nanoparticle cores and hydrogel shells composed of poly-N-isopropylacrylamide or poly[2-(2-methoxyethoxy)ethyl methacrylate] were synthesized. Citrate-stabilized gold nanoparticles and polystyrene particles were used as reference samples.
3：List of Experimental Equipment and Materials:
A pump-probe dynamic light scattering setup equipped with a HeNe laser (
4：8 nm) and a frequency-doubled Nd:
6YAG laser (532 nm), TEM for imaging, UV-vis spectrophotometer for absorbance measurements.
5：Experimental Procedures and Operational Workflow:
Samples were prepared by diluting and filtering, then placed in a goniometer setup for angle-dependent measurements. The pump laser's power was varied to study its effect on particle motion.
6：Data Analysis Methods:
Intensity-time autocorrelation functions were analyzed using the method of cumulants and compressed exponential functions to determine relaxation times and diffusion coefficients.
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