We consider the plasmonic eigenvalue problem for a general 2D domain with a curvilinear corner, studying the spectral theory of the Neumann–Poincaré operator of the boundary. A limiting absorption principle is proved, valid when the spectral parameter approaches the essential spectrum. Putting the principle into use, it is proved that the corner produces absolutely continuous spectrum of multiplicity 1. The embedded eigenvalues are discrete. In particular, there is no singular continuous spectrum.

中文翻译：

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拐角处的等离子体特征值问题：限制吸收原理和基本谱中的绝对连续性

我们考虑了带有边界的Neumann–Poincaré算子的谱理论，考虑了具有曲线角的普通2D域的等离子特征值问题。证明了极限吸收原理，当光谱参数接近基本光谱时有效。运用该原理，证明了拐角产生了绝对连续的多重度1谱。嵌入的特征值是离散的。特别地，没有奇异的连续光谱。