FT-IR Spectrometers

E. Jiang, Principles, Experiments and Applications Based on Research-Grade Nicolet FT-IR Spectrometers, Thermo Electron, Madison, WI (2003). 

In the mid-IR, routine infrared spectroscopy nowadays almost exclusively uses Fourier-transform (FT) spectrometers. This principle is a standard method in modem analytical chemistry45. Although some efforts have been made to design ultra-compact FT-IR spectrometers for use under real-world conditions, standard systems are still too bulky for many applications. A new approach is the use of micro-fabrication techniques. As an example for this technology, a miniature single-pass Fourier transform spectrometer integrated on a 10 x 5 cm optical bench has been demonstrated to be feasible. Based upon a classical Michelson interferometer design, all... 

Complex formation between Co and chelating agents was investigated by FT-IR spectroscopy after the second impregnation followed by drying. The dried sample was diluted with KBr powder and then formed into a self-supporting wafer. FT-IR measurements were carried out in a transmittance mode on an FTS6000 FT-IR spectrometer (Varian) with spectral resolution and accumulation time of 4 cm 1 and 1,024, respectively. 

Chemicals used in this study were obtained from Aldrich Chemical Company. 1H NMR spectra were obtained on a Varian EM-360, 13C NMR spectra were obtained on a JEOL-FX-60Q or a GE QE-300. An Analect FX-6200 FT-IR spectrometer was used for infrared spectroscopy and a Hewlett-Packard Model 5980 with a model 5970 mass-selective detector was used for GC-MS. TGA measurements were performed on a Perkin-Elmer TGA-7 instrument. HPLC measurements were obtained using a Waters Instrument. 

An important use for FT-IR spectrometers is in coupling them to gas chromatographs in what is called a coupled or hyphenated technique, i.e. GC-IR (p. 117). This enables the spectra of eluting peaks to be recorded without the need to trap the component or stop the gas flow. Computer enhancement and manipulations of the recorded spectra are additional features of both stand-alone FT-IR spectrometers and GC-IR systems. 

Infrared microscopy combines an optical microscope with an FT-IR spectrometer enabling pico- to femtogram (10 12—10 15 g) quantities of substances to be characterized or very small areas of larger samples to be analysed. Beam-condensing optics focus the radiation onto an area of the sample identified using the optical microscope and either reflectance or transmittance spectra can be recorded. The highly-sensitive MCT detector (p. 283) is normally used as its size can be matched to that of the radiation beam to maximize its response. 

Figure 5. Schematic diagram of the adaptation of a Nicolet 7199 FT-IR spectrometer for photoacoustic measurements on solid samples.

SEM photographs were taken on a Cambridge Instruments Stereoscan 60 Machine. UV spectra were recorded using a HP 8452A spectrometer, IR spectra were recorded on a Nicolet FT-IR spectrometer and NMR spectra were taken on Bruker AM-360. Chlorine and carbon elemental analyses were used to determine the chlorine content. 

IR spectra of the samples with and without pyridine were recorded on an FT-IR spectrometer (PE 430) with a resolution of 1 cm. In order to measure the pyridine adsorption, the samples were pressed into thin pellets, and placed into a quartz cell with CaF2 windows. The sample pellets were evacuated at 400°C for 2 h (< 10 Torr). After cooling down to room temperature, the pellets were exposed to pyridine environment (10 Torr) at 25°C. IR spectra were recorded after adsorption of pyridine for 1 h and evacuation at 150, 250, 350, and 450°C for 1 h. 

NMR spectra were recorded on Bruker Digital FT-NMR Avance 400 spectrometer (CDClj solvent) with TMS as internal reference. In the C spectra qnatemaiy, methylene and methyl carbons were identified using DEPT experiments. IR spectra were recorded on Perkin Elmer FT-IR spectrometer (KBr). Reactions were performed under dry nitrogew Melting points were measured on a Gallenkamp melting point apparatus. Sihca gel 60 (Merck) was used for column separations. TLC was conducted on standart conversion aluminium sheets pre-coated with a 0.2 mm layer of sihca gel. 

This process has a classical on-line instrumentation gathering measurements of liquid flow rates (at the input of the reactor and in the recirculation loop), temperature and pH in the reactor and biogas flow rate and composition i.e., CO2, CH4 and H2 content in the biogas) [30]. In addition, the following sensors were installed over the years a TOC analyzer, a titrimetric sensor [3] and a FT-IR spectrometer [29]. Since 1998, this instrumentation provides us with the following on-line measurements in the liquid phase every... 

For each redundancy, a belief is then defined on a two-dimensional state-universe. When dealing with the AD process previously presented, this relation is used for volatile fatty acids, total and partial alkalinity provided by the titrimetric sensor and the FT-IR spectrometer. 

The total acidity of different samples was measured by NHj-TPD with Micromeritics Autochem II (ASAP 2920) chemisorption system. The pyridine FT-IR spectra of the catalysts were recorded on a BIO-RAD FT3000 FT-IR spectrometer after desorption at 250 and 450°C, respectively. Then the total and strong acidity of Eewis and Bronsted acid was obtained from the integrated absorbance of the respective bands. 

PS118, PS160, PS340, PS463, PS537, and PS732) were obtained from Petrarch Systems, Inc. For the IR spectra a Nicolet MX-10 FT-IR spectrometer was used at a resolution of 1 cm". The UV spectra were measured on a Model DMS 90 Varian Associates UV-Visible spectrophotometer which was connected to an Apple 11+ desktop computer, equipped with an in-house modified Varian Associates software package. Other experimental details are described elsewhere(3). 

ASTM E 1421-94, Standard Practice for Describing and Measuring Performance of Fourier Transform Infrared (FT-IR) Spectrometers Level Zero and Level One Tests, 1994. 

FT-Raman spectra are measured at room temperature on a FT-IR spectrometer (Bruker IFS66) equipped with an FT-Raman accessory (Bruker FRA 106) using a Nd-YAG laser (emission wavelength 1064 nm). The data are collected in the backscattering mode (180° excitation resolution 4 cm- 256 scans 19 mW). 

The infrared spectra were recorded by an evacuable FT-IR spectrometer, Broker IFS-113v, equipped with a liquid nitrogen cooled MCT (mercury cadmium telluride) detector. All infrared spectra showed were obtained by substraction of the background (oxide) spectrum, recorded at the same temperature. 

Fourier Transform Infrared Spectroscopy (FT-IR) measurements were made using a Nicolet Instruments 740 FT-IR spectrometer. A horizontal attenuated toted reflectance cell equipped with a 45° zinc-selenide crystal trough wets used. Spectra of neat solutions were obtained by co-addition of 256 scans at 4 cm- resolution. 

Infrared spectroscopy. IR spectra were recorded on a Nicolet 5DX FT-IR spectrometer. A thin coating of the condensed silanes was applied on KBr pellets made from a very high purity KBr powder (J. T. Baker Chemical Co.). The spectra of these pellets were recorded using the transmission method. Liquid silanes were analyzed using the internal reflection attachment (IRA). The number of scans was chosen to be 20 for both background and samples. 

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