Surface enhanced infrared absorption (SEIRA) is a phenomenon by which infrared absorption of molecules adsorbed onto metal evaporated films is greatly enhanced. To clarify the enhancement mechanism in the evaporated films, we simulated the distribution of the enhancement field between Au nano-square columns by rigorous coupled wave analysis (RCWA). No maximum enhancement was observed on the particle surface. This result demonstrates that the first layer effect is not dominant for the increase in this system of columns. Furthermore, the enhanced field oscillates periodically between the particles. This periodic oscillation is not plasmon behavior seen in the visible region. Results indicate the existence of enhancement mechanisms other than plasmons and indicate the possibility that the interference effect enhances infrared absorption.

表面增强红外吸收（SEIRA）是吸附在金属蒸镀膜上的分子的红外吸收大大增强的现象。为了阐明蒸发膜中的增强机制，我们通过严格耦合波分析（RCWA）模拟了 Au 纳米方柱之间的增强场分布。在颗粒表面上没有观察到最大的增强。该结果表明，第一层效应对于该柱系统的增加并不占优势。此外，增强场在粒子之间周期性振荡。这种周期性振荡不是可见光区域中看到的等离子体行为。结果表明存在等离子体激元以外的增强机制，并表明干涉效应增强红外吸收的可能性。