Diffuse Reflectance FTIR DRIFT Spectroscopy

Surface species formed on the sample during the CO hydrogenation was observed by the diffuse reflectance FTIR (DRIFT) spectroscopy with a high-pressure chamber equipped with ZnSe window (Spectra-Tech Inc.) (18-23). After the sulfidation of Ae precursor in the same manner as described above, the... 

Among them, diffuse reflectance FTIR spectroscopy (DRIFTS) has been very popular, as is the case in the field of heterogeneous catalysis in general. Changes in surface chemistry of activated carbons, oxidized with different agents (HNO3, H2O2, and ammonium persulfate), were studied by DRIFTS in addition to Boehm titration, potentiometric titration, and water adsorption measurements... 

Surface sensitive FTIR spectroscopy is, so far, the best non-destructive surface-sensitive technique that can provide useful and specific information. While the study of the surface chemistry of Li or noble metal electrodes requires the use of methods such as external or internal reflectance, the study of the composite electrodes used in Li-ion batteries requires the use of the highly problematic diffuse reflectance mode (DRIFT) [59]. Because of that, the study of surface films formed on carbon electrodes can benefit so much from preceding studies of the surface films formed on lithium or noble metal electrodes in the same solutions. 

Diffuse reflectance infra-red spectroscopy (DRIFT) was used to characterize the powder surface chemistry and powder surface-dispersant interaction. The unexposed samples were transferred to the FTIR ultra high purity nitrogen purged sample chamber with minimal air exposure. The exposed samples were run under dry air conditions. 02-exposed powder was analyzed with the same procedure used for unexposed powder. 

Vibrational Spectroscopy. Infrared absorption spectra may be obtained using convention IR or FTIR instrumentation the catalyst may be present as a compressed disk, allowing transmission spectroscopy. If the surface area is high, there can be enough chemisorbed species for their spectra to be recorded. This approach is widely used to follow actual catalyzed reactions see, for example. Refs. 26 (metal oxide catalysts) and 27 (zeolitic catalysts). Diffuse reflectance infrared reflection spectroscopy (DRIFT S) may be used on films [e.g.. Ref. 28—Si02 films on Mo(llO)]. Laser Raman spectroscopy (e.g.. Refs. 29, 30) and infrared emission spectroscopy may give greater detail [31]. 

The problems discussed above may be circumvented by eliminating the mobile phase before measuring the spectra of the eluites, as first demonstrated by Shafer et al. [379] for pSFC-FTIR. Each eluite was deposited on a moving glass plate, on which a layer of powdered KC1 or KBr had been laid down from methanol slurry for diffuse reflectance spectroscopy (SFC-DRIFTS). Solvent elimination SFC-FTIR after deposition of the eluites on to a moving ZnSe substrate is quite straightforward the window is moved to the... 

Samples were characterized by FTIR spectroscopy with a Perkin Elmer (Spectrum BX) spectrometer using KBr pressed disks as matrices. The DRIFT experiments were carried out with a Broker IFS 55 spectrometer equipped with a Thermo Spectra Tech reacting cell. UV-vis Diffuse Reflectance spectra were recorded on a Perkin Elmer Lambda 45 spectrophotometer equipped with a diffuse reflectance attachment. Raman spectra were collected with Perkin Elmer system 2000 NIR FT-Raman using as excitation radiation the 5th harmonic of a diode pumped Nd YAG laser (1065 nm). 

The introduction of Fourier Transform Infrared Spectroscopy (FTIR) brought along a number of typical solid sample techniques. DRIFTS (Diffuse Reflectance Fourier Transform Infrared Spectroscopy) is probably most commonly known. Another technique, developed specifically for measuring solid, opaque samples is PAS (Photo Acoustic Spectroscopy). This accessory is less known, probably due to its high cost and its rather difficult modus operandi. 

Low levels of reflected energy, even from micro samples, can be measured by FTIR instruments. This method is termed diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. A reflectometer design with hemiellipsoidal mirrors sliding back for sample positioning is very convenient (Fig. 4.1.4). 

One of the major sample-handling problems in FTIR analysis of carbonaceous materials is that many of them are effective blackbody absorbers and thus are too opaque for direct transmission analysis in the midinfrared spectral region. Addition of KBr intensifies the signal to obtain transmission infrared spectra. It is time consuming, and grinding conditions and moisture are known to affect the spectrum of the sample [238]. Alternative techniques such as specular reflectance, diffuse reflectance (DRIFT), photoacustic spectroscopy (FTIR-PAS), and total... 

The adsorption of furan, 2,5-dihydrofuran and tetrahydrofuran on sodium-ion exchanged faujasites with different Si/Al ratios was studied by combining temperature-programmed desorption (TPD), inelastic neutron scattering (INS), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), quantum mechanical computations and Monte-Carlo simulations. 

IR spectroscopy is one of the few analytical techniques that can be used for the characterization of solid, liquid, and gas samples. The choice of sampling technique depends upon the goal of the analysis, qualitative identification or quantitative measurement of specific analytes, upon the sample size available, and upon sample composition. Water content of the sample is a major concern, since the most common IR-transparent materials are soluble in water. Samples in different phases must be treated differently. Sampling techniques are available for transmission (absorption) measurements and, since the advent of FTIR, for several types of reflectance (reflection) measurements. The common reflectance measurements are attenuated total reflectance (ATR), diffuse reflectance or diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and specular reflectance. The term reflection may be used in place of reflectance and may be more accurate specular reflection is actually what occurs in that measurement, for example. However, the term reflectance is widely used in the literature and will be used here. 

Identification of the specific species of the adsorbed oxyanion as well as mode of bonding to the oxide surface is often possible using a combination of Fourier Transform Infrared (FTIR) spectroscopy, electrophoretic mobility (EM) and sorption-proton balance data. This information is required for selection of realistic surface species when using surface complexation models and prediction of oxyanion transport. Earlier, limited IR research on surface speciation was conducted under dry conditions, thus results may not correspond to those for natural systems where surface species may be hydrated. In this study we review adsorbed phosphate, carbonate, borate, selenate, selenite, and molybdate species on aluminum and iron oxides using FTIR spectroscopy in both Attenuated Total Reflectance (ATR) and Diffuse Reflectance Infrared Fourier Transform (DRIFT) modes. We present new FTIR, EM, and titration information on adsorbed arsenate and arsenite. Using these techniques we... 

FTIR Fourier transform infrared spectroscopy transmission, diffuse reflection (DRIFTS), and attenuated total reflection (ATR) Identiflcation/structure of (adsorbed) species, adsorbate-adsorbent interaction... 

The primary components and the chemical structure of the raw peat and the solid product were further analyzed by Fourier transform infrared spectroscopy (FTIR) 0ASCO 670 Plus) using the Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) technique and the JASCO IR Mentor Pro 6.5 software for spectral analysis. The cross polarization/magic angle spinning (CP/MAS) NMR spectrum of raw peat and the solid... 

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