Presented here are angle dependence studies on the surface enhanced Raman (SER) signal obtained from dye placed on plasmon active nanocavity arrays. A comparative study was carried out between two modified array supports. One array had dye placed only on the interior walls of the cavities in the array. The other array had dye placed only on its top flat surface. Results show that Raman intensities as a function of angle depend on the location of the dye on the array; this was interpreted to arise from the presence of different plasmon polariton modes in these sites.

Gold nanocavity arrays were prepared on fluorine-doped tin oxide on glass by electrochemical deposition of gold through monolayers of polystyrene spheres. The impact of the resulting spherical cap architecture on the photophysics of solutions and self-assembled monolayers of luminophore encapsulated within the nanocavities is reported for the first time. From conventional confocal fluorescence microscopy, the emission intensity of solutions of [Ru(bpy)(2)(Qbpy)](2+) (where bpy is 2,2'-bipyridyl and Qbpy is 2,2':4,4'':4,4''-quarterpyridyl) and fullerene (C(60)) encapsulated within the 820 nm diameter nanocavities was demonstrated to increase by approximately an order of magnitude compared with that of the associated bulk solution. Comparison was also made with the emission observed for luminophore solution encapsulated in cobalt nanocavities of comparable dimensions, where plasmonic interactions are not anticipated. Again, approximately an order of magnitude enhancement was observed for the gold arrays. Luminescence lifetime imaging revealed that the enhancement of the emission intensity of this solution within the nanocavity was accompanied by a small but significant decrease in the luminescent lifetime for [Ru(bpy)(2)(Qbpy)](2+). Enhancement was, in addition, strongly influenced by the wavelength of excitation, suggesting that plasmonics may play a role in the enhancement of the excitation process. An important observation from confocal imaging studies was that the dimensions of the luminophore emission field from solution within the cavities were significantly smaller than the dimensions of the cavity aperture and corresponded to a little more than that of the point spread function of the microscope. This indicates that its origin is significantly smaller than the wavelength of the emitted light and suggests that luminescence enhancement is highly localised. When the array was filled with a solution of [Ru(bpy)(2)(Qbpy)](2+) the emission spectrum of this complex was red shifted and broadened compared with that of the bulk solution, typical of the formation of a luminescent surface film. In addition, significant enhancement was only observed when the solution was sonicated into the array. Both these observations suggest that the emission enhancement is localised near the bottom of the cavity. Self-assembled monolayers of [Ru(bpy)(2)(Qbpy)](2+) were formed on the array and approximately 7 orders of magnitude enhancement of the Raman signal was achieved. Significantly, the emission intensity was approximately 4-fold higher for the monolayer than for a solid film under the same conditions, but surface quenching is thought to play a significant role in the observed decrease in lifetime for the monolayer of this complex on the array.

Presented here are studies of the impact of excitation angle on surface enhanced Raman and luminescence spectroscopy of dye immobilised on a plasmon active nanocavity array support. Results show that both Raman and luminescence intensities depend on the angle of incidence consistent with the presence of cavity supported plasmon modes. Dependence of scattering or emission intensity with excitation angle occurs over the window of observation.

Presented here are studies of the impact of incident angle on surface enhanced emission from a dye that is located site selectively on a plasmon active nanocavity array support. Studies were performed for a surface active luminescent dye selectively assembled on the top surface or on the walls of the voids of nanocavity array substrates. Results show that emission intensities depend on where the dye is located with respect to the void or surface of the nanocavity array and on the dimensions of the cavity. This was interpreted to arise from the presence of void localised plasmons and surface localised and delocalised plasmon modes.Corresponding author James rice@ucd.ie

Selective chemical modification of a gold nano-cavity array is achieved via nanoscale templating to create fibrinogen patterned cavities with a polyethylene glycol modified top surface. Application of a reducing potential to the array readily releases the protein from the cavities.