STM fluorescence of porphyrin enhanced by a strong plasmonic field and its nanoscale confinement in an STM cavity

作     者：H. W. Liu R. Nishitani T. Z. Han Y. Ie Y. Aso H. Iwasaki 

作者机构：The Institute of Scientific and Industrial Research Osaka University Osaka 567-0047 Japan WPI-Advanced Institute for Materials Research Tohoku University Sendai 980-8577 Japan Department of Mathematics Physics and Computer Aided Science Faculty of Engineering Kyushu Institute of Technology Fukuoka 804-8550 Japan 

出 版 物：《Physical Review B》 (物理学评论B辑：凝聚态物质与材料物理学)

年 卷 期：2009年第79卷第12期

页      面：125415-125415页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

基　　金：Japan Science and Technology Agency 

主　　题：fluorescence nanostructured materials organic compounds photoluminescence plasmons scanning tunnelling microscopy 

摘      要：We have investigated scanning tunneling microscope-induced luminescence (STML) from porphyrin molecules by varying the tip (PtIr, Ag, and Au)/substrate (Pt, Ag, Au, and indium tin oxide) combinations. Strong molecular fluorescence by highest-occupied molecular orbital and lowest-unoccupied molecular orbital transition comparable to plasmon-mediated light is emitted only when both the substrate and the tip are metals but not in other cases. Along with calculations of relative electromagnetic-field powers in the tip-substrate gaps, the enhancement of STML from molecules can be interpreted in terms of the strong plasmon field and its confinement in an STM cavity. We also find rather strong energy-forbidden fluorescence of porphyrin in an Au-tip/porphyrin/Au cavity that occurs under the extremely strong field in the plasmonic nanocavity.