title: Fluorescence enhancement in hot spots of AFM-designed gold nanoparticle sandwiches.
abstract: We observe an enhancement of fluorescence from a single fluorescent sphere, which is sandwiched between two individual gold nanoparticles, forming a hot spot of strong field enhancement. The fluorescence enhancing hot spot is custom-designed by the deliberate assembly of gold nanoparticles with an atomic force microscope cantilever. The fluorescence intensity is monitored while the separation between the two gold nanoparticles is reduced by gradually pushing the gold nanoparticles closer to the fluorescent sphere. The fluorescence enhancement is maximal when the distance between the two gold nanoparticles is smallest, when the excitation polarization is parallel to the axis of the sandwich, and when the fluorescent sphere is positioned exactly on the axis connecting the two gold nanoparticles.
authors.affiliation: Photonics and Optoelectronics Group, Physics Department and CENS, Ludwig-Maximilians-Universität München, Amalienstrasse 54, 80799 Munich, Germany.
authors.forename: Alpan
authors.initials: A
authors.lastname: Bek
authors.forename: Reiner
authors.initials: R
authors.lastname: Jansen
authors.forename: Moritz
authors.initials: M
authors.lastname: Ringler
authors.forename: Sergiy
authors.initials: S
authors.lastname: Mayilo
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Klar
authors.forename: Jochen
authors.initials: J
authors.lastname: Feldmann
mesh_terms: D003460:Crystallization / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D018625:Microscopy, Atomic Force / Q000379:methods*; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D006046:Gold