Reflection absorption spectroscopy

Acronyms IRRAS, IRAS (infrared reflection-absorption spectroscopy) 

FT RAIRS (Fourier transform reflection-absorption infrared spectroscopy) 

Measurement of sample layers of thickness ranging from many times the wavelength down to fractions of a monolayer placed on a mirror. Absorption by the sample reduces the mirror s reflectance. 

Range of operation of incident radiation typically mid-infrared. 

In a typical set-up (constructed as an accessory to be mounted in the sample compartment of a commercial FT spectrometer), infrared radiation is focused on the sample surface at a defined angle. The reflected beam is focused onto a detector. Irradiation with a polarized IR beam is often used. 

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KJ. Uram, L. Ng, and J.R.Yates Jr., Electrostatic effects between adsorbed species-The K-CO interaction on Ni(lll) as studied by infrared reflection - absorption spectroscopy, Surf. Sci. 177, 253-277 (1986). 

Recent work in our laboratory has shown that Fourier Transform Infrared Reflection Absorption Spectroscopy (FT-IRRAS) can be used routinely to measure vibrational spectra of a monolayer on a low area metal surface. To achieve sensitivity and resolution, a pseudo-double beam, polarization modulation technique was integrated into the FT-IR experiment. We have shown applicability of FT-IRRAS to spectral measurements of surface adsorbates in the presence of a surrounding infrared absorbing gas or liquid as well as measurements in the UHV. We now show progress toward situ measurement of thermal and hydration induced conformational changes of adsorbate structure. The design of the cell and some preliminary measurements will be discussed. 

K. and Enyo, M. (1989) Surface species produced on Pt electrodes during HCHO oxidation in sulfuric add solution as studied by infrared reflection-absorption spectroscopy (IRRAS) and differential electrochemical mass spectroscopy (OEMS)./. Electroanal. Chem., 258, 219-225. 

Watanabe, S., Inukai, J. and Ito, M. (1993) Coverage and potential dependent CO adsorption on Pt(llll), (711) and (100) electrode surfaces studied by infrared reflection absorption spectroscopy. Surf. Sci., 293, 1-9. 

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].)...

Bhzanac BB, Arenz M, Ross PN, Markovic NM. 2004b. Surface electrochemistry of CO on reconstructed gold single crystal surfaces studied by infrared reflection absorption spectroscopy and rotating disk electrode. J Am Chem Soc 126 10130-10141. 

Watanabe M, Zhu Y, Uchida H. 2000. Oxidation of CO on a Pt-Fe alloy electrode studied by surface enhanced infrared reflection-absorption spectroscopy. J Phys Chem B 104 1762-1768. 

Vidal F, Busson B, Tadjeddine A, Peremans A. 2003. Effect of a static electric field on the vibrational and electronic properties of a compressed CO adlayer on Pt(l 10) in nonaqueous electrolyte as probed by infia ed reflection-absorption spectroscopy and infi ared-visible sum-fi equency generation spectroscopy. J Chem Phys 119 12492-12498. 

Different experimental approaches were applied in the past [6, 45] and in recent years [23, 46] to study the nature of the organic residue. But the results or their interpretation have been contradictory. Even at present, the application of modem analytical techniques and optimized electrochemical instruments have led to different results and all three particles given above, namely HCO, COH and CO, have been recently discussed as possible methanol intermediates [14,15,23,46,47]. We shall present here the results of recent investigations on the electrochemical oxidation of methanol by application of electrochemical thermal desorption mass spectroscopy (ECTDMS) on-line mass spectroscopy, and Fourier Transform IR-reflection-absorption spectroscopy (SNIFTIRS). 

The three most commonly applied external reflectance techniques can be considered in terms of the means employed to overcome the sensitivity problem. Both electrically modulated infrared spectroscopy (EMIRS) and in situ FTIR use potential modulation while polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) takes advantage of the surface selection rule to enhance surface sensitivity. 

Other recent applications of FT-IR in pharmaceutical analysis include reaction monitoring by fiberoptic FT-IR/ATR spectroscopy140 and stability studies of pharmaceutical emulsions using FT-IR microscopy.141 A novel equipment cleaning verification procedure using grazing angle fiberoptic FT-IR reflection-absorption spectroscopy was described by Perston et al.142... 

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