Light-assisted micronanoscale temperature control in a complex nanoparticle network has attracted a lot of research interest. Many efforts have been put into the optical properties of nanoparticle networks, and only a few investigations have reported its light-induced thermal behavior. We consider a two-dimensional (2D) square-lattice nanoparticle ensemble made of typical metal Ag with a radius of 5 nm. The effect of complex multiple scattering and thermal accumulation on light-induced thermal behavior in plasmonic resonance frequency (around 383 nm) is analyzed through the Green's function approach. The regime borders of both multiple scattering and thermal accumulation effects on the photothermal behavior of the 2D square-lattice nanoparticle ensemble are figured out clearly and quantitatively. The dimensionless parameter $\phi$ is defined as the ratio of a full temperature increase to that without considering the multiple scattering or thermal accumulation to quantify the multiple scattering and thermal accumulation effects on photothermal behavior. The more compact the nanoparticle ensemble is, the stronger the multiple scattering effect on thermal behavior is. When the lattice spacing increases to dozens times of the radius, the multiple scattering becomes insignificant. When $\phi \approx 1$ (lattice spacing increases to hundreds times of the radius), the thermal accumulation effects are weak and can be neglected safely. The polarization-dependent distribution of the temperature increase of nanoparticles is observed only in the compact nanoparticle ensemble, while for a dilute ensemble, such a polarization-dependent temperature increase distribution can no longer be observed. This work may help with the understanding of the light-induced thermal transport in the 2D particle ensemble.

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二维纳米粒子集合的光热行为：多重散射和热积累效应

复杂纳米粒子网络中的光辅助微纳米尺度温度控制引起了很多研究兴趣。已经对纳米粒子网络的光学特性进行了许多努力，只有少数研究报告了其光致热行为。我们考虑由半径为 5 nm 的典型金属 Ag 制成的二维 (2D) 方晶格纳米粒子集合体。通过格林函数方法分析了复杂多重散射和热积累对等离子体共振频率（约 383 nm）中光诱导热行为的影响。多次散射和热累积效应对二维方形晶格纳米粒子集合体的光热行为的影响范围清晰且定量地计算出来。无量纲参数$\phi$定义为完全温度升高与不考虑多次散射或热累积的情况的比率，以量化多次散射和热累积对光热行为的影响。纳米粒子集合越致密，多重散射对热行为的影响越强。当晶格间距增加到半径的几十倍时，多重散射变得微不足道。什么时候$\phi \approx 1$（晶格间距增加到半径的数百倍），热积累效应较弱，可以忽略不计。仅在致密的纳米粒子集合中观察到纳米粒子温度增加的偏振相关分布，而对于稀释的集合，不再观察到这种偏振相关的温度增加分布。这项工作可能有助于理解 2D 粒子集合中的光诱导热传输。