Fourier-transform infrared transmittance

The hydrogen content Ch greatly influences structure and consequently electronic and optoelectronic properties. An accurate measurement of Ch can be made with several ion-beam-based methods see e.g. Arnold Bik et al. [54]. A much easier accessible method is Fourier-transform infrared transmittance (FTIR) spectroscopy. The absorption of IR radiation is different for different silicon-hydrogen bonding configurations. The observed absorption peaks have been indentified [55-57] (for an overview, see Luft and Tsuo [6]). The hydrogen content can be determined from the absorption peak at 630 cm , which includes... 

Willey R R 1976 Fourier transform infrared spectrophotometer for transmittance and diffuse reflectance measurements Appl. Spectrosc. 30 593-601... 

Modern NIR equipment is generally robust and precise and can be operated easily by unskilled personnel [51]. Commercial instruments which have been used for bioprocess analyses include the Nicolet 740 Fourier transform infrared spectrometer [52, 53] and NIRSystems, Inc. Biotech System [54, 55]. Off-line bioprocess analysis most often involves manually placing the sample in a cuvette with optical pathlengths of 0.5 mm to 2.0 mm, although automatic sampling and transport to the spectrometer by means of tubing pump has been used (Yano and Harata, 1994). A number of different spectral acquisition methods have been successfully applied, including reflectance [55], absorbance [56], and diffuse transmittance [51]. 

Fourier transform infrared microscopy is the primary infrared technique for structural identification of materials at microquantities. The method is non-destructive and non-invasive. When using a proper transmittance sampling technique and a proper detector, the limit of detection can be as low as the picogram level. In the pharmaceutical industry, FTIR microscopy is used to analyze bulk drugs, excipients, and particulate contaminants. " Recent studies have shown that by coupling FTIR microscopy with GC, HPLC, SFC, or GPC systems, the detection limit of the method is substantially improved. ... 

Infrared and Raman spectroscopy, coupled with optical microscopy, provide vibrational data that allow us to chemically characterise geochemical sediments and weathered samples with lateral resolutions of 10-20 pm and 1-2 pm respectively. Fourier transform infrared spectroscopy involves the absorption of IR radiation, where the intensity of the beam is measured before and after it enters the sample as a function of the light frequency. Fourier transform infrared is very sensitive, fast and provides good resolution, very small samples can be analysed and information on molecular structure can be obtained. Weak signals can be measured with high precision from, for example, samples that are poor reflectors or transmitters or have low concentrations of active species, which is often the case for geochemical sediments and weathered materials. Samples of unknown... 

Fourier transform infrared spectroscopy (FT-IR) is useful for identifying organic and inorganic compounds by comparison with library references. Perkin Elmer System 2000 offers near IR, mid IR, far IR 15,000-15,030 cm, transmittance (T), specular reflectance (SR Ref. 6) and diffuse reflectance (DR), horizontal and vertical attenuated total reflectance (ATR) microscope (>10-gm spot, 10,000-10,580 cmy ... 

Acid sites and hvdroxvl distribution were evaluated by FT-IR (Fourier Transform-InfraRed) spectroscopy (mod. 2000 Perkin-Elmer). The spectra were recorded in transmittance at 21°C after in situ treatments of pure wafers of calcined samples. The acid sites distribution was determined by pyridine adsorption at 200°C and stepwise desorption (in the 200-500°C range, 1 h, dynamic vacuum 2-10 mbar) on pure pellets, after evacuation (500°C, 1 h, dynamic vacuum 2T0 mbar). 

Fourier transform infrared (FTIR) analysis works on the fact that chemical bonds and groups of chemical bonds vibrate at characteristic frequencies. During FTIR analysis, a modulated infrared (IR) beam is spotted on the specimen. The transmittance and reflectance of the infrared rays at different frequencies is then translated into an IR absorption plot consisting of reverse peaks, which after matching and identification provides information about the chemical bonding or molecular structure of materials, whether organic or inorganic. 

The chemical modification of the clay can be studied with the help of Fourier transform infrared spectroscopy (FTIR). In FTIR spectra of co-treated and mono-treated clays, the transmittance bands at 2922 cm and 2854 cm correspond to asymmetric and symmetric stretching vibration of methylene groups (Figure 9.5). Carbonyl stretching shows a band at 1715 cm. Both the mono-treated and co-treated montmorillonites have the absorbance bands of methylene, which is due to the successful tethering of octodecylammonium and aminoimdecanoic acid to the clay platelets [24]. 

The Fourier transform infrared (FT-IR) spectroscopy (Perkin-Elmer, GX Model) was used to examine the changes in functional gronps that may have been caused by the treatments. The samples were ground and mixed with KBr. The resultant powder was pressed into transparent pellets and analyzed in transmittance mode within the range of 4000600 cm. ... 

A Fourier transform infrared spectrophotometer (FTIR, model-IR Prestige-21, Schimadzu Corporation, Japan) was used for the structural determination of functional groups and compounds. The FTIR spectra of modified and unmodified clay in the solid state using potassium bromide (KBr) as a reference material were recorded by diffuse reflectance spectroscopy (DRS technique). This technique consists of preparation of sample by mixing about 0.5 mg of powder sample with 50 mg of high-purity infrared-grade KBr powder (Aldrich). The KBr was previously oven dried to reduce the interference of water. The spectra were recorded in the wave number range of 4000—400 cm with a resolution of 4 cm and 20 scans were carried for each sample in transmittance mode. 

UV-Vis absorbance spectroscopy measurements were performed on a Spectra Max 190 plate reader (Molecular devices, Sunnyvale, USA) operated at a resolution of 1 nm. Fourier transform infrared (FTIR) analysis of the samples dried in KBr pellet was performed on a Nicolet Model 6700 spectrophotometer in a difiuse transmittance mode at 4 cm resolution. XRD of dried silver nanoparticle samples drop-coated on glass substrate was performed on a PANalytical X pert PRO X-ray diffractometer (Netherlands), operated at 40 kV and at a current of 40 mA. TEM measurements for the samples prepared on carbon-coated copper grids were performed on a HR-TEM (JEOL-Model 3010) operated at an accelerating voltage of 200 keV. 

A Fourier transform infrared spectroscopy (FTIR) study was obtained by using Perkin-Elmer spectrometer 100, USA. Prior to this analysis, kenaf whiskers were mixed with KBr to prepare homogeneous suspensions and afterwards pressed into transparent pellets and analyzed in transmittance mode within the range of 4000-500 cm. In the case of thin nanocomposite film (Cellulose Acetate Butyrate [CAB] and kenaf whiskers) the analysis was done within the range of 4000-500 cm transmittance mode. 

Siuface functional groups of the membrane were characterized by Fourier transform infrared (FTIR, Varian 1000, Varian Inc., Palo Alto, CA) spectroscopy in attenuated total reflection (ATR) mode. Membrane surface samples were mounted on face of the crystal surface. Spectra were measured in transmittance mode over a wave length of 600-4000 cm at a resolution of 4 cm. ... 

Analysis for the purpose of accurately determining the quantity of a chemical species existing in a sample is called quantitative analysis. Quantitative infrared spectroscopic analysis mainly deals with the intensity of an infrared absorption band. In this chapter, basic aspects of quantitative spectroscopic infrared analysis for a target substance (the analyte) in solution samples are described. The subjects to be described include the characteristics of a Fourier transform infrared (FT-IR) spectrometer, the relation between percentage transmittance and absorbance, Lambert-Beer s law on the relationship between the intensity of an infrared band and the concentration of a sample, the use of a working curve in quantitative analysis, and the origins of deviations from Lambert-Beer s law. 

A typical open-path Fourier transform infrared system for remote monitoring of air pollutants uses a single unit (telescope) that functions as both a transmitter and receiver of infrared radiation (Figure 26.7). The radiation is generated by a silicon... 

An infrared spectrum is a plot of percent radiation absorbed versus the frequency of the incident radiation given in wavenumbers (cm ) or in wave length ( xm). A variation of this method, diffuse reflectance spectroscopy, is used for samples with poor transmittance, e.g. cubic hematite crystals. Increased resolution and sensitivity as well as more rapid collection of data is provided by Fourier-transform-IR (FTIR), which averages a large number of spectra. Another IR technique makes use of attenuated total reflectance FTIR (ATR-FTIR) often using a cylindrical internal reflectance cell (CIR) (e.g. Tejedor-Tejedor Anderson, 1986). ATR enables wet systems and adsorbing species to be studied in situ. 

Nowadays, most instruments use a FT-infrared (FT-IR) system, a mathematical operation used to translate a complex curve into its component curves. In an FT-IR instrument, the complex curve is an interferogram, or the sum of the constructive and destructive interferences generated by overlapping light waves, and the component curves are the IR spectrum. The standard IR spectrum is calculated from the Fourier-transformed interferogram, giving a spectrum in percent transmittance (%T) versus light frequency (cm ). 

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