DRIFT technique

McFarland M, Albritton D L, Fehsenfeld F C, Ferguson E E and Schmeltekopf A L 1973 Flow-drift technique for ion mobility and ion-molecule reaction rate constant measurements. I. Apparatus and mobility measurements J. Chem. Phys. 59 6610-19... 

Crompton [770] has described extraction of scraped TLC spots (Cyasorb UV531 and Ionol CP), followed by off-line IR analysis of KBr discs. Chalmers et al. [752] have used off-line TLC-DRIFT for extracted PP/(Irganox 1330/1010, Topanol OC, erucamide). Volatility of Topanol OC on the particle surfaces of the KC1 substrate highlights a limitation of the off-line TLC-DRIFTS technique. 

Assessing Formates as Potential Intermediates over Pt/Zr02 and Na-Doped Pt/Zr02 Catalysts Employing the SSITKA-DRIFTS Technique... 

Tibiletti, Meunier, Goguet, Burch, and coworkers—application of SSITKA-DRIFTS technique to elucidate intermediates during RWGS/WGS—dependency on catalyst type and feed conditions of the reactivity of formates/carbonates. 

The spectrum of dexamethasone obtained by the DRIFT technique is shown in Figure 5.13 and is very similar to that obtained using a KBr disc. However, the proportion of dexamethasone powdered with KBr and used to obtain the DRIFT spectrum was lO times that used to prepare the KBr disc, which yielded the spectrum shown in Figure 5.12. As discussed earlier in this chapter, the use of DRIFT has some advantages over the preparation of a KBr disc. 

IR spectrum of dexamethasone obtained using the DRIFT technique. 

Using this "spray-drift" technique, half-lives for triflura-lin conversion were measured (Table IV, 25). Under optimum sunlight conditions (August, 12 00 noon) the half-life for triflura-lin dealkylation was 21 minutes. The rate fell off later in the summer, but was still on the order of 3 hours in October. By comparison, laboratory photolysis in air containing ozone was 47 minutes, in reasonable agreement with the field. The rate was slower when no ozone was present in the reactor, and little or no reaction took place without light. 

IR spectroscopy of adsorbed probe molecules is mostly performed with either the transmission/absorption technique or with the DRIFT technique. In the tiansmis-sion/absorption technique, self-supporting pressed disks ofthe pure oxide powders... 

The constitution of oxygen-containing sites in carbonaceous materials of various types was a subject of inquiry of many authors. The first systematized results were outlined in a review by Boehm [77]. In the past few years numerous researches were carried out applying the diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) technique [78-81], and their results were summarized in a paper by Fanning and Vannice [82]. Analogous results concerning... 

The disadvantages of conventional IRS, like the need to compress the samples, is overcome when the diffuse reflectance Fourier transform (DRIFT) technique is used, whereby a few milligrams of the compound is dispersed in approximately 250 mg of KBr, and the spectrum is obtained by reflection from the surface. 

In a similar vein, Wilson et al. [61] recorded the FTIR spectra of fruit jams of different types using a diffuse reflectance (DRIFT) samphng accessory. Despite distortions in the spectra, associated with the use of the DRIFT technique, the different jams were found to exhibit characteristic and reproducible patterns, indicating that jams of different fruit content can be differentiated on the basis of their FTIR spectra. The authors suggested the potential utihty of this technique for the detection of adulteration of jams, for instance, by the substitution of fruit content by cheaper vegetable material. 

Experimentally, IR spectroscopy can be accomplished in a number of ways by Nujol mull, KBr disc or the diffuse reflectance technique. In the KBr disc technique, the compound is mixed with KBr and compressed into a disc using a press and die. This can be a disadvantage if the compound undergoes a polymorphic transformation under pressure (see Chan and Doelker, 1985). One way to overcome this problem is to use the diffuse reflectance Fourier transform (DRIFT) technique, whereby a few milligrams of compound is dispersed in approximately 250 mg of KBr and the spectrum obtained by reflection from the surface. 

The DRIFT method has proven to be extremely useful for studies of the 0-H, 0-D, C-H, and C-D stretching region (nominally 2000 to 4000 cm" ) of molecular sieve materials (1-3). Kazansky and coworkers (4-6) have employed the DRIFT technique to investigate the combination and overtone structure of the 0-H and 0-D band systems... 

Adsorption and Reactions of Methane on Ferric Molybdate using DRIFTS Technique Surajit Fuangfoo, Anand S. Chellappa and Dabir S. Viswanath ... 

Diffuse reflectance spectroscopy (DRS) has been frequently employed in UV-Vis spectroscopy of zeolites (cf. Volume 4, Chapter 4 of the present series). More recently, it became also popular in IR investigations (cf., e.g., [160, 161]). The DRIFT technique is advantageous because it is successfully applicable not only in the mid infrared but also in the near infrared (NIR) region of 4000-10,000 cm where the transmission technique usually fails because of severe scattering through the absorbent particles. The NIR range, however, is very important with respect to the study of overtone and combination modes of vibrations. Moreover, diffuse reflectance IR experiments can be carried out not only with pressed wafers as in transmission spectroscopy, but also with zeolite pow-... 

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... 

The surface nature of the DRIFT technique can be easily illustrated by some simple examples. Figure 1 shows the DRIFT spectra of two inorganic oxides silica and titania. In Figure lA the most prominent features of the spectrum of silica include the very broad band between 4000 and 3000 cm which is the result of water adsorbed on the surface. A sharp peak near 3750 cm is superimposed on this broad band and is the result of isolated silanol groups on the surface (=Si-OH) [2-4]. Since silica can be considered a polymeric... 

The following examples illustrate the power of the DRIFTS technique for analysis of interaction between fillers and surface treatments or polymer additives. 

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