Understanding and accounting for quantum effects in nanoplasmonics is essential for accurate modeling and design of nanophotonic devices. In this paper, we investigate the influence of such quantum effects as spatial nonlocality and splitting of the wave function of conduction electrons near the surface of plasmonic nanoparticles on the extinction cross-section and the field enhancement factor. We apply the theory of generalized nonlocal optical response (GNOR) to describe the spatial nonlocality of noble metal particles. To consider the behavior of electrons near the metal–dielectric interface, mesoscopic boundary conditions are used, including the surface response functions (SRF) - the Feibelman parameters. We use the discrete source method (DSM), allowing for numerical analysis of the scattering problems taking into account quantum effects in the frame of both theories. The application of both GNOR and SRF approaches leads to a decrease in the amplitude of the plasmon resonance compared to the classical Maxwell theory and its shift to the shorter wavelength region (blue shift). The simulation results demonstrate significant differences between the two theories explaining the quantum effects arising in non-spherical plasmonic nanoparticles located in a dense environment. Specifically, compared with GNOR theory, SRF predicts a larger field enhancement. We found that quantum nonlocal effects are more significant for the enhancement factor at the particle surface than for the extinction cross-section. In addition, it was discovered that a denser environment leads to a significant increase in the blue shift of the plasmonic peak.

中文翻译：

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解释等离子体纳米粒子中量子效应的理论的比较分析


了解和解释纳米等离子体中的量子效应对于纳米光子器件的准确建模和设计至关重要。在本文中，我们研究了等离子体纳米粒子表面附近传导电子的空间非局域性和波函数分裂等量子效应对消光截面和场增强因子的影响。我们应用广义非局部光学响应 （GNOR） 理论来描述贵金属粒子的空间非局部性。为了考虑金属-介电界面附近电子的行为，使用了介观边界条件，包括表面响应函数 （SRF） - Feibelman 参数。我们使用离散源法 （DSM），允许在考虑两种理论框架中的量子效应的情况下对散射问题进行数值分析。与经典的麦克斯韦理论相比，GNOR 和 SRF 方法的应用导致等离子体共振的振幅减小，并且向较短波长区域（蓝移）的偏移。仿真结果表明，两种理论之间存在显着差异，解释了位于致密环境中的非球形等离子体纳米粒子中出现的量子效应。具体来说，与 GNOR 理论相比，SRF 预测的场增强更大。我们发现，粒子表面的增强因子的量子非局域效应比消光横截面的量子非局域效应更重要。此外，还发现，较密集的环境会导致等离激元峰的蓝移显着增加。