title: Incident-angle-modulated molecular plasmonic switches: a case of weak exciton-plasmon coupling.
abstract: We have designed an angularly tunable plasmonic system that consists of Au nanodisks in combination with molecules of photoswitchable resonance, spiropyran, to gain new insights into weak exciton-plasmon couplings. In the weak exciton-plasmon coupling regime, switching molecular resonance can induce localized surface plasmon resonance (LSPR) peak shifts due to the change in the refractive index of the molecular materials. On the basis of the angle-resolved spectroscopic study of the nanodisk-spiropyran system both with and without UV irradiation, we reveal an unusual "zigzag" curve for the LSPR peak shifts (due to the photoswitching of the molecular resonance) as a function of the original LSPR peak wavelength. A further theoretical analysis attributes the "zigzag" curve to two significant competing effects that depend on the incident angle of the probe light: plasmon-enhanced molecular resonance absorption and LSPR sensitivity to the surroundings' refractive index.
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Yue Bing
authors.initials: YB
authors.lastname: Zheng
authors.forename: Brian
authors.initials: B
authors.lastname: Kiraly
authors.forename: Sarawut
authors.initials: S
authors.lastname: Cheunkar
authors.forename: Tony Jun
authors.initials: TJ
authors.lastname: Huang
authors.forename: Paul S
authors.initials: PS
authors.lastname: Weiss
mesh_terms: D006046:Gold / Q000737:chemistry*; D008027:Light; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry*; D008956:Models, Chemical; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D010825:Physics / Q000379:methods
chemical_list: D006046:Gold