Silver islands

Zeisel D, Deckert V, Zenobi R and Vo-Dinh T 1998 Near-field surface-enhanced Raman spectroscopy of dye molecules adsorbed on silver island films Chem. Phys. Lett. 283 381... 

Zero-order desorption occurs if the rate of desorption does not depend on the adsorption coverage, as seen with relatively large silver islands on a ruthenium surface (Fig. 7.7), where the Ag atoms desorb from the edges of the island. As the 0" term in Eq. (12) vanishes, the curves exhibit a clearly recognizable exponential shape on the leading side. Such situations are rare. 

Figure 2.9 Spectra of a single adenine nanocrystal, (a) TERS spectrum, (b) ordinal SERS spectrum, and (c) ordinary near-infrared (NIR) Raman spectra. For the SERS measurement, a silver island film was used. For the NIR Raman measurement, i thick sample of adenine was used with a 1 h exposure.

Figure 8. Valence band XPS (a) and UPS (b) spectra of silver islands on native oxide covered Si(l 0 0) during bombardment with 1 keV Ar" ions. Substrate related contributions are removed. Numbers at each spectra stand for the Ag/Si ratio determined from the appropriate XPS core level spectra. The uppermost curve is the spectrum of polycrystalline bulk Ag. (Reprinted from Ref [146], 1998, with permission from Elsevier.)...

Stockle R.M., Deckert V., Fokas C., Zeisel D., Zenobi R., Sub-wavelength Raman spectroscopy on isolated silver islands, Vibrational Spectrosc. 2000 22, 39-48. 

The top spectrum of Fig. 3.22 corresponds to a complete monolayer of Xe on the sample. It can be used for a quantitative titration of sites. The area under the two peaks indicates that about 27% of the Xe in the monolayer is adsorbed on silver, indicating that 27% of the ruthenium surface is covered by silver islands. As a peak at 7.25 eV, which would be characteristic of Ag-Ru boundary sites, is not observed, the results suggest that Ag is present in fairly large islands. 

Figure 7. STM Images of a silver Island on HOPG In aqueous 0.05 S AgClO. Image was obtained with a glass-coated Pt-Xr tip at a bias of 100 mV (tip +) and lt - 16 nA without removing the freshly Ag plated surface from the plating solution.

A number of promising metal structures for fluorescence signal enhancement have been proposed silver island films (SIFs) that provide about 5-15-fold enhancement [89], fractal-like structures that resulted in stronger enhancements at specific hot spots [90-92], and SIFs deposited on silver or gold films with about 50-fold enhancement [93, 94], Recently, it was found that strong enhancement on a gold film based plasmonic platform may change even the shape of the emission spectrum [95],... 

Lakowicz JR, Shen Y, D Auria S, Malicka J, Fang J, Gryczynski Z, Gryczynski I (2002) Radiative decay engineering 2. Effects of silver island films on fluorescence intensity, lifetimes, and resonance energy transfer. Anal Biochem 301 261-277... 

TERS experiments were performed to study the bacterial cell surface. Biju et al. combined silver island films on glass coverslips with an AFM to investigate the effect of electron-acceptor limitation on the outer cell membrane of Shewanella one.ide.nsis [103]. 

Other SERS-active substrate techniques include mechanical polishing polycristalline silver (Vo-Dinh et al., 1988) or ion bombardment in vacuo (Wood and Zwemer, 1981 Davies et al., 1986). A chemical procedure to prepare silver island films using Tollen s reagent was developed by Ni and Cotton (1986) which turned out to be simple, rapid and highly reproducible. In addition, the surface roughness and hence the enhancement... 

Figure 1.3. (A) Photographs of silver island films (SIFs) deposited onto glass and plastic supports. (B) Normalized absorbance of zinc, copper, gold and silver nanostructured particles on a glass support. Atomic force microscope images of SIFs on (C) glass (D) plastic support.

K. Aslan, Z. Leonenko, J. R. Lakowicz, and C. D. Geddes. Annealed silver-island films for applications in metal-enhanced fluorescence Interpretation in terms of radiating plasmons yourna/ of fluorescence, 2005, 15, 643-654. 

K. Aslan, S. N. Malyn, and C. D. Geddes. Angular-Dependent Metal-Enhanced Fluorescence from Silver Island Films Chemical physics letters, 2008,453, 222-228. 

Figure 3.1 Cartoon for an excited PTCDA molecule and the silver island dipolar response that results in significant radiation.

Figure 3.2 SEF at 514.S nm are illustrated using Langmuir-Blodgett monolayer of a PTCD derivative on silver islands with a plasmon resonance in resonance with the molecular absorption. After quenching the Fluorescence with Ag overlayers LB-SERRS, with its overtone series, is clearly seen. The pre-resonant SERS excited at 632.8 nm is also shown to highlight the differences in the intensities of fundamental and overtones bands compared to SERRS.

Silver island film using SiOx spacer layers Basic ftichsin 200 14]... 

Silver island film with 15 nm fatty acid spacer layer Phthalocyanine 400 15]... 

Silver island film peridinin-chlorophyll-pro tein 18 51]... 

Silver Island film fluorescein-labeled immunoglobulin G (Fl-IgG) 40 49]... 

The PTCDA moiety is a class of molecule that readily exhibits excimer fluorescence. A direct method to attain the enhancement factor for a substrate is to deposit a LB monolayer onto a glass slide that contains an area of a silver island film. By comparing the fluorescence intensity measured on glass and the island film under identical conditions, an excellent assessment of the EF can be attained. 

Figure 3.8 Molecular absorption of a PTCD derivative, surface plasmon of the evaporated silver film. Excimer fluorescence of an LB monolayer on glass and SERRS with the background SEF of the LB monolayer on the silver island film.

Aroca, R., Kovacs, G. J., Jennings, C. A., Loutfy, R. O., and Vincett, P. S. (1988). Fluorescence enhancement from Langmuir-Blodgett monolayers on silver island films. Langmuir 4 518-521. 

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