Infrared IRES

IRE Infrared emission [110] Infrared emission from a metal surface is affected in angular distribution by adsorbed species Orientation of adsorbed molecules... 

IRE Infrared emission IR emission spectrum observed High resolution, long... 

Infrared Spectroscopy Transmission Infrared Spectroscopy Diffuse Reflectance Infrared Spectroscopy (DRS, DRIFT) Infrared Emission Spectroscopy (IRES)... 

Measurements of supported catalysts in diffuse reflection and transmission mode are in practice limited to frequencies above those where the support absorbs (below about 1250 cm-1). Infrared Emission Spectroscopy (IRES) offers an alternative in this case. When a material is heated to about 100 °C or higher, it emits a spectrum of infrared radiation in which all the characteristic vibrations appear as clearly recognizable peaks. Although measuring in this mode offers the attractive advantage that low frequencies such as those of metal-oxygen or sulfur-sulfur bonds are easily accessible, the technique has hardly been explored for the purpose of catalyst characterization. An in situ cell for IRES measurements and some experiments on Mo-O-S clusters of interest for hydrodesulfurization catalysts have been described by Weber etal. [11],... 

Fig. 11. Modification18 of Sofica photometer for use at 0 = 1060 nm pd - monitoring photodiode, bs — beam splitter, i - iris, pm — photomultiplier, ire — infrared converter, ps - power supplies, cro - cathode ray oscilloscope, a - aperture, p — reflecting prism, c — cell...

Quantitative determinations of the thicknesses of a multiple - layered sample (for example, two polymer layers in intimate contact) by ATR spectroscopy has been shown to be possible. The attenuation effect on the evanescent wave by the layer in contact with the IRE surface must be taken into account (112). Extension of this idea of a step-type concentration profile for an adsorbed surfactant layer on an IRE surface was made (113). and equations relating the Gibbs surface excess to the absorbance in the infrared spectrum of a sufficiently thin adsorbed surfactant layer were developed. The addition of a thin layer of a viscous hydrocarbon liquid to the IRE surface was investigated as a model of a liquid-liquid interface (114) for studies of metal extraction ( Ni+2, Cu+2) by a hydrophobic chelating agent. The extraction of the metals from an aqueous buffer into the hydrocarbon layer was monitored kinetically by the appearance of bands unique to the complex formed. 

Attenuated total refectance (ATR) infrared spectroscopy has been used to identify chemical species that are adsorbed to a germanium internal reflection element (IRE). We have described a method for depositing thin... 

The sampling depth, dp, of the infrared radiation from the surface of the IRE outward can be calculated from Equation 1 (13) ... 

Attenuated total reflection infrared (IR) spectra are obtained by pressing the sample against an internal reflection element (IRE) [e.g., zinc selenide (ZnSe) or germanium (Ge)]. IR radiation is focused onto the end of the IRE. 

Light enters the IRE and reflects down the length of the crystal. At each internal reflection, the IR radiation actually penetrates a short distance ( 1 pm) from the surface of the IRE into the sample as shown in Figure 10.4 and enables one to obtain infrared spectra of samples placed in contact with the IRE. 

The IRE material must show transparent regions in the infrared and it should have a proper refractive index to allow internal reflection. It must be insoluble in the usual solvents and chemical inert to all components in the sample. However, from the list of IR-transparent materials in Table 3.4-1 only a few are recommended for IRE s. Table 6.5-1 lists most of these materials. 

Infrared emission IRES The vibrational modes of adsorbed molecules on a surface are studied Molecular structure... 

This work was supported by a grant from the National Science Foundation, t Abbreviations used are as follows. FTIR Fourier transform infrared spectroscopy, ATR attenuated total reflectance, IRE internal reflection element, SATR solution ATR FTIR, FSD Fourier self-deconvolution, PLS partial least-squares analysis, PRESS prediction residual sum of squares from PLS. SECV standard error of calibration values from PLS, PLSl PLS analysis in which each component is predicted independently, PLS2 PLS analysis in which all components are predicted simultaneously. 

It can be seen from Equations 1.2 and 1.3 that the spatial resolution of infrared microspectroscopy can be improved by immersing the sample in a medium of high refractive index. This exactly what is done in attenuated total reflection (ATR) spectroscopy using a single-reflection hemispherical internal reflection element (IRE). Eor example, if a germanium n = 4.0) hemispherical IRE is used, not only... 

Fourier Transform Infrared Emission Spectroscopy (FT-IRES)... 

There was also described and discussed the relatively new Fourier transform infrared emission spectroscopy (IRES), its principle, an appropriate FT-IRES setup and applications. FT-IRES is unique in that it does not require an external radiation source, because the sample itself is the source. The radiation emitted from the sample is collected and sent to the detector. The ratio of the sample signal to that from a black body source represents the spectrum. However, appli-... 

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