Activity: Talk or presentation › Oral presentation
Silver nanocrystal arrays of 5 nm diameter Ag nanoparticles surrounded by a shell of dodecanethiol are formed by drop-casting. This gives an ordered system of close-packed spherical nanocrystals that enables a thorough analysis of the electromagnetic inter-particle interactions. The position of the two plasmon resonances observed in these nanocrystals is the result of their collective interaction. This collective interaction leads to a low and a high energy plasmon resonance, excited by the electric field components parallel and perpendicular to the interface, respectively. The magnitude of the plasmon resonance splitting previously observed using a variety of different techniques is also found in ellipsometry spectra. We analyzed that the peak separation in the silver nanocrystal arrays is comparable to the optical response of isolated, non-interacting oblate nanocrystals. The optical deformation of the spherical particles as a result of the interaction can be compared with oblate particles that have a depolarization factor of 0.25 parallel to the interface. The ellipsometry measurement shows a better resemblance between calculation and measurement as compared to polarized reflection measurements. Most likely, this is due to the sensitivity for diffuse scattering of the latter technique.
28 Mar 2007
DPG Frühjahrstagung 2007 Regensburg: (DPG Spring Meeting)