深紫外光増感作用を目的としたアルミニウムナノ構造のデザイン：高さ制御によるプラズモン共鳴の短波長シフトの観察

摘要

金属のナノスケールの構造物に光をあてると，光と金属表面の自由電子の固有振動が結合して，光電場を増強したり局在化させたりすることができる．この現象は局在プラズモン共鳴（Localized Surface Plasmon Resonance：LSPR）と呼ばれ　この原理を利用して化学センサーや可視光感光材料，分光分析ツールなどの幅広い応用が実現している．%Light couples with free electrons in metals on the nanometer scale, exhibiting a localization and enhancement effect known as Localized Surface Plasmon Resonance (LSPR). LSPR has been exploited in many scientific and industrial fields, such as sensors, optical waveguides, high-sensitivity optical detection, high-resolution microscopy, etc. In spite of the versatility of LSPR, the applicable wavelength range of LSPR has been limited to the visible and infrared because the host materials for conventional LSPR, mainly gold and silver, do not exhibit metallic behavior at ultraviolet (UV) wavelengths. We used aluminum as a new candidate LSPR material at UV wavelengths and optimized its structure for better coupling with light from UV to deep-UV. Aluminum nanostructures were fabricated by a nanoparticle lithography method. In this report, we especially focus on the relationship between the LSPR wavelength and the height of the nanostructures. By increasing the height of the nanostructures, blue shifts of the LSPR wavelength were observed. With finer tuning of the nanostructures, an LSPR wavelength of 244 nm was successfully achieved, which is the shortest reported LSPR wavelength.