Infrared Reflection-absorption spectroscopy IRAS

Acronyms IRRAS, IRAS (infrared reflection-absorption spectroscopy)... 

With these favorable circumstances, the HREEL spectrum of poiyimide reveals a large number of vibrational bands, quite well resolved from each other. In order to help band assignments, IR transmission spectrum, or Fourier Transform IRAS (Infrared Reflection Absorption Spectroscopy) spectra, from model ODA, PMDA and PMDA-ODA surfaces can be used. These last spectral data have been superimposed on the HREEL spectrum, in the 1000-2(XX) cm i region, where a number of vibrational bands do signiflcandy overlap (Fig. 2). It is quite clear that all the different chemical sites have their fingerprints t... 

Pt-Ru alloy [158-160] or Ru modified Pt surfaces [161] are known to be prominently effective catalysts for methanol oxidation. Watanabe and Motoo [87] introduced a bifunctional mechanism into electrochemical interfaces in that Ru in Pt-Ru alloy surfaces supplies OH moieties to promote CO oxidation on neighboring Pt surfaces. In this context, it is crucial to elucidate water or hydroxide that are anticipated to adsorb on Ru in the alloy or modified Pt electrode surfaces. Nevertheless, there have been substantial uncertainties on this point because of experimental constraints in vibrational spectroscopy relevant for this purpose, e.g., poor sensitivity or uncompensated interruption by bulk solution species in IRAS (infrared reflection absorption spectroscopy). Watanabe and co-workers recently reported that water molecules were detected on the Pt-Ru alloy surfaces, a finding... 

Methanol oxidation was investigated recently by IRAS (Infrared Reflection Absorption Spectroscopy) and TPD (Temperature Programmed Desorption)... 

IRAS Infrared reflection-absorption spectroscopy (same as RAIRS)... 

Figure 10.20 (A) Temperature-programmed desorption (TPD) and (B) Infrared reflection absorption spectroscopy (IRAS) spectra of CO adsorbed on Au/FeO(111) as a function of Au coverage. (Reprinted from Lemire, C. et al., Angew. Chem. Int. Ed., 43, 118-121,2004. With permission from Wiley-VCH.)...

Amino-amido-thiol HS —(CH2)io CO— NH—CH2—NH2 adsorbed on Au(lll) has been studied by sum frequency generation and infrared reflection absorption spectroscopy (IRAS) in the CH2 stretching vibration region [151]. 

The ILs interact with surfaces and electrodes [23-25], and many more studies have been done that what we can cite. As one example, in situ Fourier-transform infrared reflection absorption spectroscopy (FT-IRAS) has been utilized to study the molecular structure of the electrified interphase between a l-ethyl-3-methylimidazolium tetrafluoroborate [C2Qlm][BF4] liquid and gold substrates [26]. Similar results have been obtained by surface-enhanced Raman scattering (SERS) for [C4Cilm][PFg] adsorbed on silver [24,27] and quartz [28]. 

Many similar studies have been done at surface science conditions using step-function concentration signals. For example, Takagi et al. (52) studied the adsorption and desorption of CO on Ni(lOO) via infrared reflection absorption spectroscopy (IRAS). In one case, CO dosing was turned on for 214 s and then turned off. The response of the spectrum of the surface intermediate was followed by IRAS. Of course, under these high-vacuum... 

IRAS = IRRAS infrared reflection-absorption spectroscopy 3.7c.i... 

On metal surfaces, two additional selection rules apply. The first is that only vibrations perpendicular to the surface are HREELS active. This rule follows from two phenomena unique at metal surfaces (i) Electromagnetic waves polarized perpendicularly to the plane of incidence (parallel to the plane of the surface) undergo a 180° phase shift upon reflection. That is, at the metal surface, the out-of-phase electric-field vectors of the incident and reflected waves cancel each other as a result, no field exists that can couple with dipoles that oscillate parallel to the surface, (ii) The dynamic dipole moment generated by an oscillator that vibrates in the surface-parallel direction is cancelled by that of its image dipole (Figure 1) hence, there the net dynamic dipole moment is zero. On the other hand, if the real dipole is oriented perpendicularly to the surface, its dynamic dipole moment is reinforced by that of its image dipole. This selection rule is the same as that for infrared reflection-absorption spectroscopy (IRAS). =... 

This technique is used to study thin (down to submonolayer) films adsorbed on reflective substrates such as metals. Experimentally it involves measuring the change in the reflectance spectrum of the substrate that accompanies thin film formation. Various acronyms for the technique are used infrared reflection—absorption spectroscopy (IRRAS, IRAS) and reflection—absorption infrared spectroscopy (RAIRS). The Basics of IRRAS spectra are described in Chapter 5.2. 

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