Reflectivity, infrared drying

Infrared drying, ceramics processing, 5 656 Infrared dyes, 9 500 Infrared emission spectroscopy, 23 142 Infrared inks, 14 315 Infrared lasers, 22 180 Infrared LEDs, 22 175, 176 Infrared measurements, in growing amorphous silicon, 22 130 Infrared microspectroscopy, 16 486 Infrared reflection-absorption spectroscopy (irras), 24 72, 114-116. See also IR spectra... 

Internal reflection infrared spectra measured in situ during etching of silicon in HF solutions exhibit characteristic Si - H modes, although the Si - H spectrum is broad because of interaction of the surface Si-H groups with the electrolyte. No electrochemical or chemical intermediate species have been detected [112]. Infrared spectra of porous silicon layers after drying reveal characteristic Si-H and Si-H2 peaks similar to the spectra obtained for hydrogen on Si(lOO) 2x1 surfaces [112]. 

Detailed experimental procedures for obtaining infrared spectra on humic and fulvic acids have been reported previously 9,22,25-26) and will be briefly described here. Infrared spectra were taken on the size-fractionated samples by using a Fourier transform infrared spectrometer (Mattson, Polaris) with a cooled Hg/Cd/Te detector. Dried humic and fulvic materials were studied by diffuse reflectance infrared spectroscopy (Spectra Tech DRIFT accessory) and reported in K-M units, as well as by transmission absorbance in a KBr pellet. Infrared absorption spectra were obtained directly on the aqueous size-fractioned concentrates with CIR (Spectra Tech CIRCLE accessory). Raman spectra were taken by using an argon ion laser (Spectra-Physics Model 2025-05), a triple-grating monochromator (Spex Triplemate Model 1877), and a photodiode array detector system (Princeton Applied Research Model 1420). All Raman and infrared spectra were taken at 2 cm resolution. 

Cylindrical internal reflectance infrared spectroscopy presents many advantages over conventional infrared techniques for the study of aquatic humic and fulvic materials. Samples can be studied in their natural state and in the aqueous environment from which they are isolated. Sample alterations due to drying and exposure to high pressures in the pellet forming process are avoided. In addition. 

Figure 64. Typical diffuse reflectance infrared spectrum of a dried water-based drilling fluid. (Reproduced with permission from reference 181. Copyright 1991 Society of Petroleum Engineers.)...

Generally speaking, the methods used to characterize carbonaceous material surfaces are referred to as wet and dry techniques. The former include potentiometric titrations and zeta potential or electrochemical methods the latter include temperature-programmed desorption (TPD) and spectroscopic methods such as x-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared spectroscopy (DRIFT). 

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... 

DRIFT Diffuse reflectance infrared fourrier transform spectroscopy Drug carriers Materials loaded with pharmaceutical compounds Dry strength Strength of the fully hardened sand-binder mixture DTA Differential thermal analysis... 

Self-supporting pressed discs of the pure oxide powders are prepared for in situ characterisation studies by transmission/absorption IR spectroscopy. These samples are put onto the IR beam, in an appropriate cell allowing heating, cooling, and gas/vapour manipulation. Activation is mostly performed by outgassing at relatively high temperatures. In the case of diffuse reflectance infrared Fourier transform (DRIFT) experiments the pure catalyst powder is deposited on the sample holder, with smooth pressure, and activation is mostly performed by an inert, dry gas flow. 

Recently, for the first time. Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy was applied to characterize tin oxide-based thick film gas sensors under normal working conditions (between 25 and 300 C in dry and humid air) [103]. The obtained results confirm the role of surface hydroxil groups in the CO detection ... 

Initial attempts at producing a catalytic chitosan film were carried out using a glass substrate and an Al substrate. A lwt% solution of chitosan was made up in 1% aqueous acetic acid and was cast onto the substrates and allowed to dry, initially at room temperature, and then at 60°C. Clear films were successfully formed in both cases, and were moderately resistant to abrasion, and completely resistant to soaking in hot solvents (water, ethanol, toluene, THF at 50 C for 72h had no effect on the film). Diffuse reflection infrared studies indicated the presence of chitosan on the substrates before and after immersion in solvents. 

The evanescent wave sticks up above the surface of the crystal by less than a micron to upwards of 10 microns depending upon the experiment. To take the spectrum of a sample it is brought into contact with the hot spot, some of the beam is absorbed by the sample, and the beam is then focused on the detector. The background spectrum is obtained of the clean, dry crystal. Since the sample absorbances attenuate the intensity of the totally reflected infrared beam the term attenuated total reflectance (ATR) is used. An example of how an ATR crystal can be used to take the spectrum of a sample is shown in Figure 4.49. 

Downey, G., Dublin, I. Authentication of coffee bean variety by near-infrared reflectance spectroscopy of dried extracts. J. Sci. Food Agric. 71 (1), p. 41 —49, 1996... 

To put things into perspective, we. can broadly classify these analytical methods into bulk, dry surface, and in situ interfacial techniques. This chapter focuses on the last category, illustrating two in situ techniques used to study anion binding at the goethite (a-FeOOH)-water interface titration calorimetry and cylindrical internal reflection-Fourier transform infrared (CIR-FTIR) spectroscopy. In fact, CIR-FTIR could prove to be extremely powerful, since it allows direct spectroscopic observation of ions adsorbed at the mineral-water interface. 

For n = 15 cereal samples from barley, maize, rye, triticale, and wheat, the nitrogen contents, y, have been determined by the Kjeldahl method values are between 0.92 and 2.15 mass% of dry sample. From the same samples near infrared (NIR) reflectance spectra have been measured in the range 1100 to 2298 nm in 2nm intervals each spectrum consists of 600 data points. NIR spectroscopy can be performed much easier and faster than wet-chemistry analyses therefore, a mathematical model that relates NIR data to the nitrogen content may be useful. Instead of the original absorbance data, the first derivative data have been used to derive a regression equation of the form... 

PVI-1 and UDI have been Investigated as emtl-oxldatlon agents for Cu in dry air at elevated temperatures [ -30]. Fourier transform Infrared reflection-absorption spectroscopy TFT-IR RAS) was... 

Two types of samples are in common use for analysis by the I440F and each includes customized software and sample holders calibrated for individual instruments. The sampling methods include use of (a) dry, powdered samples (approximating those in use in common near infrared reflectance analyzers), and (b) wet monolayers which are essentially samples placed on a large scale microscope slide and a cover glass. 

NIR spectra are acquired using dried tissue, either whole or ground. The reflectance is measured relative to a so-called white reference, which is a highly reflective surface, such as Gore-Tex or white ceramic. Near-infrared reflectance spectra, or absorbance spectra, defined as log(l/R), with R being the reflectance, look rather flat. For analysis purposes the second derivative of the spectra is often used, because it enhances certain spectral features. 

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