Diffuse Reflectance Infrared Fourier Transform Spectroscopy DRIFTS

4 Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) 

The results of the DRIFTS analysis are expressed in % R, which shows the quantity of energy reflected and is equivalent to % T (transmittance)  

Is = intensity of infrared radiation reflected by the sample 7b = intensity of infrared radiation reflected by a reference (mirror, KBr), also called background  

The results of the DRIFTS analyses reported in literature are also expressed in % A (absorbance) and Kubelka-Munk (K-M), which relates /(/ oo) functions with concentration and the scattering factor of the samples, and it is used for quantitative analyses  

Analyses performed by DRIFTS have the advantage of minimum sample preparation, without requiring pellets. It may be applied to analyze samples in powder form or those deposited in a matrix, and some examples of material analyzed may be cited, such as medicinal products, high molecular weight organic material, plastics, crystals, and dyes (whose pigments usually cause transmittance distortions). 

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Diffuser aerators, jet air, 26 165 Diffuse reflectance, 14 231 Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), 24 72, 110-111... 

DRIFT spectra, acquiring, 24 111. See also Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) Drilling, of hydrothermal wells, 12 525-527 Drilling fluid (drilling mud) companies, 9 2 Drilling fluid materials, 9 2, 9-25. See also Drilling fluids Drilling muds alkalinity control in, 9 19 barite, 9 9-10 calcite, 9 10... 

Direct NIR or MIR measurements of whole soil can be made using attenuated total reflectance (ATR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) samplers. This type of measurement detects only components on the surface and so has severe limitations when information about the bulk soil is needed [4],... 

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is used to obtain spectra of powders and rough polymeric surfaces such as textiles and paper. IR radiation is focused onto the surface of the sample in a cup resulting in both specular reflectance (which directly reflects off the surface having equal angles of incidence and reflectance) and diffuse reflectance (which penetrates into the sample subsequently scattering in all angles). Special mirrors allow the specular reflectance to be minimized. 

Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT).6 When IR radiation is directed onto the surface of a solid sample, two types of energy reflectance can occur specular and diffuse. The specular component is the radiation that reflects directly off the sample surface (i.e., not absorbed by the sample). Diffuse reflectance is the radiation that penetrates into the sample and then emerges. Diffuse reflectance accessories are designed to optimize the diffuse reflected energy and suppress the specular component. The optics therefore selectively directs the scattered radiation to the IR detector. 

Chan, T. Y. Chen, R. Sofia, M. J. Smith, B. C. Glennon, D. High Throughput On-Bead Monitoring of Solid Phase Reactions by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), Tetrahedron Lett. 1997, 38, 2821. 

Cradun, R., Miller, D.J., Dulamita, N. and Jackson, J.E. (1996) Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) applied in heterogeneous catalysis studies. Prog. Catal., 5, 55. 

Therefore, X-ray photoelectron spectroscopy (XPS) [12, 16,17] and diffuse reflection infrared Fourier transform spectroscopy (DRIFT) [17] are used to analyse the chemical composition of the metal surface and the amount of the surface-bonded polymer after the adsorption processes. For the ZnO/PVFA-co-PVAm composites solvatochromic dyes were employed to evaluate changes in the surface polarity after the polymer adsorption [18-22],... 

A number of experimental alternatives to traditional IR transmission spectroscopy are suitable for overcoming some of these complicating experimental factors. In the technique of diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) (Hartauer et al. 1992 Neville et al. 1992) the sample is dispersed in a matrix of powdered alkali halide, a procedure which is less likely to lead to polymorphic transformations or loss of solvent than the more aggressive grinding necessary for mull preparation or pressure required to make a pellet (Roston et al. 1993). For these reasons, Threlfall (1995) suggests that DRIFTS should be the method of choice for the initial IR examination of polymorphs. He has also discussed the possible use of attenuated total reflection (ATR) methods in the examination of polymorphs and provided a comparison and discussion of the results obtained on sulphathiazole polymorphs from spectra run on KBr disks, Nujol mulls and ATR. 

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... 

High quality IR spectra of different carbon surfaces were obtained by photo-thermal beam deflection spectroscopy (IR-PBDS) [123,124]. This technique was developed with the intention of providing an IR technique that could be used to study the surface properties of materials that are difficult or impossible to examine by conventional means. Recently, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) has been successfully applied to study the effect of different pretreatments on the surface functional groups of carbon materials [101,125-128]. Several studies aiming to improve the characterization of the carbon electrode surface and the electrode-electrolyte interface have been carried out using various in situ IR techniques [14,128-132]. The development of in situ spec-troelectrochemical methods has made it possible to detect changes in the surface oxides in electrolyte solutions during electrochemical actions. 

TY Chan, R Chen, MJ Sofia, BC Smith, D Glennon. High throughput on-bead monitoring of solid phase reactions by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Tetrahedron Lett 38 2821-2824, 1997. 

For some sample types, for example a coated substrate, it is not possible to collect an infrared transmission spectrum, whereas in some cases (e.g. when there are concerns over the effects of sample preparation) it may be more desirable to collect a reflected spectrum. The most popular reflection techniques nowadays are internal reflection spectroscopy (IRS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)... 

This section summarizes the chemistry of the SC isobutane regeneration process. To understand the nature of the hydrocarbons that remain adsorbed on the surface of the USY zeolite catalyst both before and after SC isobutane regeneration, a series of ex-situ temperature-programmed oxidation (TPO), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and ultraviolet-visible (UV-vis) analyses was performed on samples submitted to different TOS 10 under isobutane/butene reaction conditions. 

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies were performed at 373 K on a Nicolet Magna 750 Fourier transform infrared spectrometer equipped with a commercial Spectratech diffuse reflectance cell. Eight-hundred-scan spectra were collected in the 4000-400 cm range at a resolution of 4 cm. The catalyst samples were diluted in KBr at a ratio of about 1 200 sample KBr for DRIFTS analyses. 

The catalysts were characterized by N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), temperature-programmed desorption of ammonia (NH3-TPD), X-ray diffraction (XRD), Raman spectroscopy, in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and X-ray photoelectron spectroscopy (XPS). The procedures and experimental conditions have been detailed elsewhere [9]. 

Lennard C J, Mazzella W D and Margot P A 1993 Some applications of diffuse reflectance infrared Fourier transform spectroscopy DRIFTS in forensic science Analysis 21 M34-7... 

Accordingly, transient kinetic techniques which are able to provide unique information on the actual state of a working catalyst within a very short period of time [13,14] were applied to this complex and unstable catalytic system. Non-steady-state and steady-state isotopic transient kinetics (NSSTK and SSITK) combined with in situ diffuse reflectance infrared Fourier transformed spectroscopy (DRIFT) and temporal analysis of product (TAP) were performed in order to analyse some of the above mentioned key steps of the aromatisation process. 

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. 

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