DRIFT diffuse reflectance infrared Fourier

DRIFTS Diffuse reflectance infrared Fourier-transform Same as IR Same as IR... 

Although acetone was a major product, it was not observed by infrared spectroscopy. Flowing helium/acetone over the catalyst at room temperature gave a prominent carbonyl band at 1723 cm 1 (not show here). In this study, a DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) cell was placed in front of a fixed reactor DRIFTS only monitored the adsorbed and gaseous species in the front end of the catalyst bed. The absence of acetone s carbonyl IR band in Figure 3 and its presence in the reactor effluent suggest the following possibilities (i) acetone formation from partial oxidation is slower than epoxidation to form PO and/or (ii) acetone is produced from a secondary reaction of PO. 

DRIFT diffuse reflectance infrared Fourier transform... 

DRIFT Diffuse reflectance infrared Fourier-transformed specaroscopy... 

Secondly, compared to methanol oxidation, the rates of reaction decrease significantly upon oxidation of HMF for the Pt and Pd catalysts. In the case of Pt this decrease is drastic under the mild conditions applied here, indicating a strong interaction of HMF with the Pt surface. In the case of Pd the decrease is less pronounced and for Pd/Al-N even an increase in rate of reaction is found (entries 3 and 15). Probably the interaction of HMF with Pd is less strong, especially in the case of highly dispersed Pd. In order to study the interaction of HMF with noble metals, DRIFT (diffuse reflectance infrared fourier transform) measurements are in progress. 

Diffuse reflection involves reflecting the infrared beam off of a solid sample, as in specular reflection, but it is the nonspecular portion of the reflected radiation that is collected. When an ftir spectrometer is used, diffuse reflection is called DRIFTS (diffuse reflectance infrared Fourier-transform... 

Hydrated silica gel was modified with APTS (sample 1) and studied by DRIFT (Diffuse Reflectance Infrared Fourier Transform) and CP MAS NMR. The IR spectrum of the modified silica (figure 9.4) shows silane NH, CH and Si-O-Si bands along with silica lattice and surface vibrations. Assignments of IR bands of APTS modified silica are given in table 9.2. 

DRIFTS diffuse reflection infrared Fourier transform spectrsocopy... 

The heterogenization of MAO-activated Nd(z 3-C3H5)3 dioxane on MAO-functionalized Si(>2 was reported by T. Riihmer et al. [307]. In situ DRIFT (= diffuse reflectance infrared Fourier transform) spectroscopy and TPRS (= temperature-programmed reaction spectroscopy) were employed... 

NH3-DRIFT (Diffuse Reflectance Infrared Fourier Transform) spectra were collected with a Brucker IF S88 spectrometer performing 200 scans with a resolution of 4 cm. Pure samples were placed inside a commercial controlled environmental chamber (Spectra-Tech 0030-103) attached to a diffuse reflectance accessory (Spectra-Tech collector). To investigate the stability of the adsorbed ammonia species during temperature elevation, the spectra were recorded under helium (30ml/min) at room temperature, 373, 473, and 573 K, after exposure to an ammonia flow for 30 min at room temperature. 

DRIFTS (Diffuse Reflectance Infrared Fourier Transform) Spectroscopy... 

Diffuse reflectance or DRIFTS (diffuse reflectance infrared Fourier-lransform spectroscopy) allows the sain)le to be analysed neat, ot diluted in a non-absorbing matrix (e.g. KCl or KBr at 1-5% w/w analyte). DRIFTS also may be used to obtain the spectrum of a solute in a volatile solvent by evaporating the solution onto KBr. When the IR radiation interacts with the powdered sample it will be absorbed, reflected and diffracted. The radiation which has been diffusely reflected contains vibrational information on the molecule. This technique allows non-destructive testing of neat materials and is suited to quantitative analysis, although care must be taken to ensure that a consistent particle size is used. 

The diffuse reflectance method (DRIFTS - diffuse-reflectance infrared Fourier-transform spectroscopy) is a popular alternative sampling technique [31] that requires no specific sample preparation or only a dilution with a non-absorbing material (e.g. KBr or KCl). The main disadvantage of DRIFTS is the sensitivity to particle-size effects, which must be considered for quantitative assays. 

DRIFT Diffuse reflection infrared Fourier transform spectroscopy... 

Direct, in situ HPTLC-FTIR measurement is carried out by diffuse reflectance using a DRIFT (Diffuse Reflection Infrared Fourier Transform Spectroscopy) unit (Fig. 15) (40-45). It is necessary to take account of the fact that at wavelengths where the absorption is large and the refractive index is high, the incident radiation is almost 100% normally reflected at the surface so that there is scarcely any diffuse reflection, which is that part of the reflection that contains the spectral information concerning the sample, in contrast to the normal (Fresnel) reflection. This means that reflectance minima and not the expected reflectance maxima are obtained at wavelengths of strong absorption. With silica gel, the absorption maxima, also known as residual radiation bands, dominate appreciably in the 1300-... 

---