SERS Investigations

The technique of photoemission electron spectroscopy (PEEM) is a particularly attractive and important one for spatially resolved work function measurements, as both the Kelvin probe technique and UPS are integral methods with very poor ( mm) spatial resolution. The PEEM technique, pioneered in the area of catalysis by Ertl,72-74 Block75 76 and Imbihl,28 has been used successfully to study catalytic oscillatory phenomena on noble metal surfaces.74,75 

It has also been recently employed to investigate NEMCA by Imbihl and coworkers.28 Both porous Pt paste films and evaporated microstructured Pt electrodes prepared by microlithography were investigated. These microstructured electrodes were typically 500 A thick. 

With both types of electrodes Imbihl and coworkers28,29 found good agreement with the work function-change potential-change equality 

The figure shows the observed variations in local work function within the three marked squares (1 is mostly on YSZ, 2 and 3 are on Pt). As shown in this figure and also in Fig. 5.47 the local work function (which increases with decreasing local brightness) follows the imposed variation in UWR. 

Increasing UWr increases h, according to Eq. (5.18), thus causes local darkening (less electrons are emitted) as expected (Fig. 5.47c). Decreasing Uwr decreases h, again according to Eq. (5.18) as expected (Fig. 5.47b). 

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The cyanide ion was one of the first adsorbed ions which was found to be surface enhanced (8,9) on silver electrodes. In this first stage of SERS investigation of the cyanide ion, it was assumed to be linearly bonded to Ag, through the carbon atom, perpendicular to the metal surface (9). However faced with the pressure of explaining the SERS mechanism, alternative structures were proposed. With the conception of the ad-atom model for SERS, Otto conjectured that the main SERS band was due... 

Recently, the SERS effect has been used increasingly for highly sensitive sensor devices for biological and medical applications as well as in practical analytical chemistry (Alivisatos, 2004 Emory and Nie, 1998 Faulds et al., 2004 Ishikawa et al., 2002 Kneipp et al., 1995 Wang et al., 2003), and the field of catalysis certainly will see a comparable increase in SERS investigations of active metal catalysts (vide infra). 

Bolboaca M, Iliescu T, Kiefer W (2004) Infrared absorption, Raman, and SERS investigations in conjunction with theoretical simulations on a phenothiazine derivative. Orem Phys 298 87-95... 

Bozzini B, Romanello V, Mele C (2007) A SERS investigation of the electrodeposition of Au in a phosphate solution. Surf Coat Tech 201 6267-6272... 

Same laser for Raman and one optical tweezers 787 nm Two different kinds of Bacillus stearothermophilus (bacterial spores) SERS investigation of bacterial spores regarding spore coat composition in two. Discrimination between the two was possible... 

AFM microscopy is more suited for the morphological study of solid surfaces, such as metallic plates with variable roughness therefore, it is extremely helpful when used in combination with the SERS investigation. In this way, the SERS... 

The Raman techniques combined with AEM microscopic imaging, as for instance TERS (tip-enhanced Raman scattering) spectroscopy [27], allow to analyze surface nanostructures beyond the diffraction limit, but the cost of the instrumental apparatus is not affordable for any research laboratory. Therefore, in this chapter, the results obtained with those techniques will not be presented, though they increased Raman enhancement factors by up to lO, with the possibility of single-molecule detection. Conversely, confocal micro-Raman apparatus is affordable to every research group allowing SERS investigations with more comparable results. 

In this section, it will be shown as most information at nanometer level coming from electronic or atomic force microscopy, previously described, may be easily transferred to micro-SERS investigation. 

Muniz-Miranda M, Giorgetti E, Margheri G, Del Rosso T, Sottini S, Giusti A, Alloisio M (2005) SERS investigation on the polymerization of carbazolyl-diacetylene monolayers on gold surfaces. Macromol Symp 230 67-70... 

The peptide backbone vibration (amide 1) and the ring-breathing mode of phenylalanine at 1004 cm are not enhanced in this chromosome. An interpretation of this missing enhancement is that only the DNA has a strong interaction with the surface. The protein contents do not interact directly with the surface. These Micro-SERS investigations have shown that SERS can clarify structural changes of chromosomes in the adsorbed state. 

Fleisehmann, M., MengoU, G., Musiani, M.M. and Lowry, R.B. (1987) An electrochemical and SERS investigation of the influenee of pH on the effectiveness of some corrosion inhibitors of copper. Journal of Electroarudytical Chemistry, 217, 187. 

SERS investigations were carried out using either preroughened electrodes [10, 57-59] or smooth electrodes (e.g., vitreous carbon or Pt) which became SERS-active upon the deposition of Ag or Au nuclei (islands) [13,61, 63,64]. SERS was used to study the nucle-ation of metal deposits and the evolution of deposit morphology during electrodeposifion ... 

Electrodeposition on smooth, SERS-inactive substrates has been described as a method for obtaining good-quality SERS spectra of pyridine adsorbed onto Ru, Rh and Pd [67]. However, to date no SERS investigations on the electrodeposition of metals other than Au, Ag and Cu have been reported. 

In 1990, Fleischmann et al. used NIR Fourier transform SERS (NIR FT-SERS) [71] to study the Cu corrosion inhibitors, benzotriazole and tolyltriazole. Diagnostic bands were identified for each compound, whereby benzotriazole and tolyltriazole were coadsorbed and found to displace each other, depending on their relative concentrations. The NIR FT-SERS investigations were extended to an antifreeze (ethylene glycol) mixture [24], in which both benzotriazole and tolyltriazole were identified by SERS as being adsorbed... 

Bozzini, B., Pietro De Gaudenzi, G. and Mele, C. (2004) A SERS investigation of the electrodeposition of Ag-Au alloys from free-cyanide solutions. Jounud of Electroanalytical Chemistry, 563,133-143. 

Bozzini, B., D Urzo, L., Mele, C. and Romanello, V. (2008) A SERS investigation of cyanide adsorption and reactivity during the electrodeposition of gold, silver, and copper from aqueous cyanocomplexes solutions. The Journal of Physical Chemistry C, 112, 6352-6358. 

Gui, J. and Devine, T.M. (1995) A SERS investigation of the passive films formed on iron in mildly alkaline solutions of carbonate/bicarbonate and nitrate. Corrosion Science, 37, 1177-1189. 

M. Baia, S. Astilean, T. lliesku. New developments in SERS-active substrates, in Raman and SERS Investigations of Pharmaceuticals (Springta, Bca lin, 2008), pp. 187—205 M.J. Banholzer, J.E. Millstone, L. Qin, C.A. Mirkin, Rationally designed nanostructures for surface-enhanced Raman spectroscopy. Chem. Soc. Rev. 37, 885 (2008)... 

M. Baia, S. Astilean, T. Illescu, Raman and SERS Investigations of Pharmaceuticals (Springer, Berlin, 2008)... 

Different types of mimetic systems of biological membranes including vesicles (spherical phospholipid bilayers), LB monolayers, hybrid bilayers (HBLs) and tethered lipid bilayers were used in SERS investigations. LB films are monomolecular films that can be fabricated from amphiphiles at the water-air interface and transferred to a SERS solid substrate (such as island film). For SERS studies, the target molecule was treated as a dopant in a monolayer matrix formed for example by arachidic acid or phospholipids. Aroca and co-workers applied the LB technique to detect SERRS signal firom a variety of chromophores such as several perylene derivatives and RH6G even in SM level in some cases (Aroca 2006). HBLs are monolayers of phospholipids incorporated into SAM of long-chain thiols such as... 

S. Caporali, V. Moggi-Cecchi, M. Muniz-Miranda, M. Paghali, G. Pratesi, V. Schettino, SERS investigation of possible extraterrestrial life traces experimental adsorption of adenine on a Martian meteorite. Meteorit. Planet. Sci. 47, 853 (2012)... 

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