ABSTRACT
Surface-enhanced Raman scattering (SERS) with deep-UV excitation is of particular interest because a large variety of biomolecules such as amino acids exhibit electronic transitions in the UV spectral range and resonant excitation dramatically increases the cross section of the associated vibrational modes. Despite its potential, UV-SERS is still little-explored. We present a novel straightforward scalable route to fabricate aluminum nanovoids for reproducible SERS in the deep-UV without the need of expensive lithographic techniques. We adopt a modified template stripping method utilizing a soluble template and self-assembled polymer spheres to create nanopatterned aluminum films. We observe high surface enhancement of approximately 6 orders of magnitude, with excitation in the deep-UV (244 nm) on structures optimized for this wavelength. This work thus enables sensitive detection of organics and biomolecules, normally nonresonant at visible wavelengths, with deep-UV surface-enhanced resonant Raman scattering on reproducible and scalable substrates.
ABSTRACT
Rapid adsorption kinetics have been observed for protein binding to a 800 nm aggregated nanoparticle, showing extreme sensitivity resulting from a non-linear particle plasmon response.
Subject(s)
Fibrinogen/chemistry , Gold/chemistry , Metal Nanoparticles/chemistry , Serum Albumin, Bovine/chemistry , Surface Plasmon Resonance , Animals , Cattle , Colloids/chemistry , Protein BindingABSTRACT
The emission of light from whispering-gallery modes excited in microscopic spheres is examined. An evanescent wave is produced by total internal reflection of an optical beam at a planar glass-air interface. This evanescent wave is used to excite whispering-gallery modes in single microscopic spheres placed behind the glass-air interface. The intensity of light emitted into the air half-space from such spheres is measured as a function of scattering angle for both p- and s-polarized input beams. These data are compared with a simple theory for the emission from a point source above a planar glass substrate.
ABSTRACT
Scattering of light from single spheres placed behind a glass-air interface with light incident through the glass is examined. This scattering is investigated for both p- and s-polarized light incident at angles below the glass-air critical angle. The intensity of light scattered into the air half-space from each sphere is measured as a function of scattering angle, and this response is compared in situ with the background scatter produced by the planar substrate. A detailed comparison between data and established theory are thereby obtained. This system is of interest in the field of optical biosensing.
