Metal films with patterns of subwavelength holes (grids or meshes) have interesting optical properties including the extraordinary transmission effect. These optically thick metal films transmit more radiation than that incident on the holes owing to the excitation of surface plasmons (SPs). Meshes present a new and simple way to excite SPs at perpendicular incidence (i.
View Article and Find Full Text PDFThe interaction of an infrared surface plasmon and an excited molecular vibration was investigated by using a square array of subwavelength holes in a Ni film which supports propagating, surface-plasmon-mediated, transmission resonances. The largest transmission resonance [the (1,0)(-)] was tuned through the rocking vibration of the hexadecane molecule (at 721 cm(-1)) in a hexadecane film on the mesh by varying the thickness of the film. The interaction of the rocking vibration and surface plasmon is characterized spectroscopically by an increase in the intensity of the vibrational band by more than a factor of 2, variation of the vibrational line shape relative to the spectrum on a nonmetallic surface, and shifts in vibrational peak position by as much as 3.
View Article and Find Full Text PDFReliable thermochemistry is computed for infinite stretches of pure-carbon materials including acetylenic and cumulenic carbon chains, graphene sheet, and single-walled carbon nanotubes (SWCNTs) by connection to the properties of finite size molecules that grow into the infinitely long systems. Using ab initio G3 theory, the infinite cumulenic chain (:C[double bond]C[double bond]C[double bond]C:) is found to be 1.9+/-0.
View Article and Find Full Text PDFThe flow of polarized light through a metal film with an array of microchannels is controlled by the phase of an optically active, phospholipid nanocoating, even though the coating does not cover the open area of the microchannels. The molecular details of the assembly (DPPC phospholipid monolayer/bilayer on a hexadecanethiol monolayer on a copper- or nickel-coated microarray) were determined using the infrared, surface-plasmon-mediated, extraordinary transmission of the metal microarrays. Infrared absorption spectra with greatly enhanced absorptions by comparison to literature were recorded and used as a diagnostic for the phase, composition, and molecular geometry of these nanocoatings.
View Article and Find Full Text PDFThe surface-plasmon-mediated, extraordinary transmission of metallic arrays of subwavelength apertures has been used as the light source for absorption studies of self-assembled monolayers on metal. Enhanced infrared absorption spectra of a sequence of alkanethiol self-assembled monolayers on copper were recorded for carbon chain lengths varying from 8 to 18 atoms. Transition positions and intensities are presented over a large range of the infrared region.
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