Fourier Transform-infrared Optical microscope

All infrared spectra were recorded with an IR-PLAN microscope (IR-PLAN is a registered trade mark of Spectra Tech, Inc.) integrated to a Perkin-Elmer Model 1800 Fourier transform infrared (FT-IR) spectrophotometer. The spectrophotometer consisted of a proprietary heated wire source operated at 1050°C, a germanium overcoated potassium bromide beamsplitter, and a narrow-band mercury-cadmium-telluride (HgCdTe) detector. The detector was dedicated to the microscope and had an active area of 250 x 250 pm. The entire optical path of the system microscope was purged with dry nitrogen. 

The experimental techniques used are optical and scanning electron microscopes, electron microprobe, potentiodynamic polarization, X-ray diffraction, Fourier transform infrared spectroscopy and transmission Mossbauer spectroscopy. 

The apparatus used for IR microscopy is a Fourier-transform infrared (FTIR) spectrometer coupled on-line with an optical microscope. The microscope serves to observe the sample in white light at significant magnification for the purpose of determining its morphology, as well as to select the area for analysis. The spectrometer, on the other hand, enables study of the sample by transmission or reflection measurement for the purpose of determining the chemical composition. It also provides information about the microstructure and optical properties (orientation) of the sample. It is possible to apply polarised light both in the observation of the sample and in spectrometric measurements. 

A Nicolet Magna 550 Fourier Transform Infrared Spectrometer (FTIR) and a Bruker MW 250 MHz proton NMR were used to verify the chemical structure of all monomers and polymers. Optical activity of the compounds was measured at 25 on a Perkin-Elmer Polarimeter in chloroform. A Waters Gel Permeation Chromatograph with 440 UV absorption detector and R401 differential refructometer was used to determine the molecular weights of the polymers tetrahydrofuran was used as the mobile phase at 1.0 mL/min, and the Waters polystyrene gel columns were calibrated with monodisperse polystyrene standards. Polarizing optical microscopy was used to identify liquid crystalline phases using a Leitz optical microscope with a CCD camera attachment... 

In many studies, particularly those related to materials and forensic science, it is frequently necessary to measure a mid-infrared spectrum from a trace amount of a sample or a sample of small size. In some circumstances, this may be accomplished by using a beam-condenser accessory within the conventional sample compartment of a Fourier-transform infrared (FT-IR) spectrometer. Perhaps today though, it is more convenient to use infrared microspectrometry (often commonly referred to as infrared microspectroscopy or even infrared microscopy). Based on an optical microscope (or infrared microscope) coupled to an FT-IR spectrometer, it is one of the most useful methods for structural analysis of such samples and can often be undertaken in a non-destructive manner [1, 2]. 

Physical and chemical characterization methods are essential to assess aspects such as material and processing quality. Raman microprobe is an analytical tool coupled to an optical microscope. Elemental analysis using the x-rays emitted from the specimens in the electronic microscopy techniques can be used for local composition determination or to obtain a map of the distribution of a certain element in a wider area wavelength and energy-dispersive x-ray spectrometers are used for these purposes. Fourier transform infrared spectrometer is widely used for the qualitative and quantitative analysis of adhesives, the identification of unknown chemical compounds, and the characterization of chemical reactions. Thermal methods such as thermomechanical analysis and differential scanning calorimetry are discussed as valuable tools for obtaining information during postfracture analysis of adhesively bonded joints. 

Infrared (IR) spectroscopy, especially when measured by means of the Fourier transform method (FTIR), is another powerful technique for the physical characterization of pharmaceutical solids [17]. In the IR method, the vibrational modes of a molecule are used to deduce structural information. When studied in the solid, these same vibrations normally are affected by the nature of the structural details of the analyte, thus yielding information useful to the formulation scientist. The FTIR spectra are often used to evaluate the type of polymorphism existing in a drug substance, and they can be very useful in studies of the water contained within a hydrate species. With modem instrumentation, it is straightforward to obtain FTIR spectra of micrometer-sized particles through the use of a microscope fitted with suitable optics. 

The optical requirements for an IR microscope include (i) exact positioning of the sample (ii) spatial isolation of the sample from a larger matrix in the IR beam and (Hi) capability to function in both the visible and the infrared spectral regions. For infrared microspectrometry, a thermal emission source is generally used. Fourier transform spectrometers use interferometers as an effective means to resolve photon energies. Mercury cadmium telluride (MCT) detectors have the sensitivity and speed needed for FTIR spectrometers. The use of synchrotron radiation dramatically improves infrared microspectroscopy and has the power to analyse and map samples at high resolution. SR sources have transformed the IR microspectrometer into a true IR microprobe, providing IR spectra at the diffraction limit. Optics and performance of a /uF llR interfaced with SR were described [423]. Some 15 synchrotron beam lines are equipped with IR microscopes. 

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