Attenuated total reflectance surface-enhanced

Figure 6.16 Attenuated total reflection surface enhanced infrared reflection absorption spectroscopy (ATR-SEIRAS) spectra for the oxidation of 0.1 M HCOOH in 0.5 M H2SO4 on a polycrystaUine electrode. The bands at 2055 -2075 and 1800-1850 cm are assigned to linear- and bridge-bonded CO, whereas the band at 1323 cm corresponds to adsorbed formate. (Reproduced from Samjeske et al. [2006].)...

Attenuated total reflection-surface enhanced infrared... 

Chen et al. [95], very recently, prepared Au thin-film electrodes made by electroless deposition for in situ electrochemical attenuated total-reflection surface-enhanced infrared adsorption spectroscopy (ATR-SEIRAS) which consisted of 46 nm Au nanoparticles deposited on a Si infrared window. Very interestingly, they observed that a square-wave treatment of the Au film led to a much enhanced ORR activity (02-saturated 0.1 M HCIO4) as a consequence of the surface reconstruction of the nanoparticle film. Thus, whereas the ORR activity of the initial Au... 

Purely electrochemical or microscopic techniques (see below) only allow a limited insight into the microbial electron transfer processes. Consequently, the use of spectroelectrochemical techniques, i.e., the direct coupling electrochemical and spectroscopic analysis, has been demonstrated. These techniques, including for instance the combination of voltammetry and UV/vis spectroscopy [19], attenuated total reflectance surface-enhanced infrared absorption spectroscopy... 

During this time period, several groups investigated the SH response from metallic films using attenuated total reflection techniques (ATR) in which the nonlinear response is enhanced by coupling into surface plasmons (or polaritons) [28-38]. Simon et al. [28] were the first to demonstrate this effect. 

A complementary approach to the standard reflection geometry described above uses the attenuated total reflection (ATR) geometry which couples surface plasmon waves to the incident electric field and enhances the SH production. Two configura-... 

Sampling in surface-enhanced Raman and infrared spectroscopy is intimately linked to the optical enhancement induced by arrays and fractals of hot metal particles, primarily of silver and gold. The key to both techniques is preparation of the metal particles either in a suspension or as architectures on the surface of substrates. We will therefore detail the preparation and self-assembly methods used to obtain films, sols, and arrayed architectures coupled with the methods of adsorbing the species of interest on them to obtain optimal enhancement of the Raman and infrared signatures. Surface-enhanced Raman spectroscopy (SERS) has been more widely used and studied because of the relative ease of the sampling process and the ready availability of lasers in the visible range of the optical spectrum. Surface-enhanced infrared spectroscopy (SEIRA) using attenuated total reflection coupled to Fourier transform infrared spectroscopy, on the other hand, is an attractive alternative to SERS but has yet to be widely applied in analytical chemistry. 

In the case of infrared spectroscopy, various types of infrared measurement methods (transmission method, attenuated total reflection (ATR) method, reflection-absorption (RA) method, surface-enhanced method, etc.) may be applied. 

Recently, Shao et al. proposed superoxide (O2) formation as the first step of the ORR on Pt films in alkaline solution (NaC104 with pH=ll) by analyzing spectral data of surface-enhanced infrared reflection absorption spectroscopy with attenuated total reflection (ATR-SEIRAS). This was fuller supported by Zhang and Anderson, who performed DFT cluster calculations for the ORR on Pt(lll), Pt(lOO), and umeconstracted Pt(llO). They... 

Vibrational spectroscopy represents two physically different, yet complementary spectroscopic techniques IR and Raman spectroscopy. Although both methods have been utilised for many years, recent advances in electronics, computer technologies and sampling made Fourier transform infrared (FTIR) and Raman (FT-Raman) one of the most powerful and versatile analytical tools. Enhanced sensitivity and surface selectivity allows non-invasive, no-vacuum molecular level analysis of surface and interfaces. Emphasis is placed on recent advances in attenuated total reflectance (ATR), step-scan photoacoustic (SS-PA), Fourier transform infrared (FTIR) and FT-Raman microscopies, as utilised to the analysis of polymeric surfaces and interfaces. A combination of these probes allows detection of molecular level changes responsible for macroscopic changes in three dimensions from various depths. 7 refs. 

The use of silver films under Kretschmann s attenuated total reflection geometry has improved the detection limit of the surface layer on polymer films. An enhancement factor 10 and 2 is reported for polydimethylsiloxane and... 

Infrared-based techniques are used to identify molecules on the surface. IR radiation is used to excite vibrational modes in molecules in the gas phase or adsorbed on a surface. The transmitted or reflected IR spectrum can be analyzed in a spectrometer. Considerable improvement in the sensitivity can be achieved by use of Fourier transform infrared (FTIR) spectroscopy. Attenuated total reflection (the ATR-FTIR method) inside a crystal (germanium) of high refractive index can be used to further enhance the surface sensitivity (using the evanescent field). 

Attenuated total reflectance (ATR) Surface enhanced Raman scattering (SERS)... 

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