Infra-red spectrophotometer

The C NMR spectra were obtained at 50.3 MHz on a Varian XL200 spectrometer. IR spectra were obtained on a Digilab F75-15 FTIR and Perkin-Elmer 1310 infra red spectrophotometer. 

For visible region the lenses and prisms of ordinary glass can be used but since glass is opaque to radiation of shorter wave lengths in ultraviolet spectrophotometers they are made of quartz. In infra red spectrophotometers they are made of large crystals of NaCl, CsF or KBr. 

The results of the characterization of the product synthesized with Fourier transformation infra-red spectrophotometer (FTIR), X-ray diffractometer (XRD), scanning electron mirror microscope (SEM) and the transmission electron mirror microscope (TEM) illustrate that the product synthesized by the process of double decomposition-precipitation with calcium nitrate and di-ammonium phosphate as the reactants in the SCISR consists of well dispersed particles of about 15 nm in diameter and 50-70 nm long, having a very regular shape and appearance and is confirmed to be hydroxylapatite. 

In the process of developing PRMs, it is necessary to study and establish measurement methods which are used to analyzed the purity of raw gases and verify the stability of the gas mixture kept in the cylinder. Up to now, NRCCRM has been equipped with several series of analytical techniques including atmospheric pressure ionization mass spectrometer, gas chromatograph, infra-red spectrophotometer with long-path gas cell, chemiluminescent, non-dispersive infra-red, minor 02 and H20 analyzer and so on. 

The basic components of a dispersive infra-red spectrophotometer are shown in Fig. 1. The source of infra-red radiation is an electrically conducting element, such as a Globar or Opperman source, which is maintained at about 1000°. 

Infra-red Spectrophotometers can be single- or double-beam instruments, or both facilities may be available. In the double-beam mode, the beam of radiation passes through both the sample and a reference path (or reference cell). The use of a reference cell enables compensation to be made for unwanted absorption, e.g. from solvents. Alternatively, an instrument fitted with computing facilities can record and remember the solvent spectrum and then subtract it from a subsequent spectrum obtained with the same cell. 

The Fourier transform infra-red spectrophotometer incorporates an interferometer (Fig. 3). Its basic components are a beam splitter and two mirrors, perpendicular to each other, one fixed and one which can be moved backwards and forwards at right angles to its plane. Approximately half of the radiation from the source is reflected to the fixed mirror where it is reflected back to the beam splitter which transmits about half (i.e. a quarter of the original) to the detector. The other half of the original radiation passes through the beam splitter to the movable mirror where it is reflected back to the beam splitter and about half (i.e. a quarter of the original) is reflected to the detector. When the two mirrors are equidistant from the beam splitter, the two beams... 

The use of data-processing equipment in conjunction with infra-red spectrophotometers, both dispersive and interferometric, produces three advantages, namely instrument control, spectrum manipulation, and spectrum identification and interpretation. Firstly, the control of the instrument is simplified and the reproducibility and accuracy of wavelength and transmission (or absorbance) are greatly enhanced. For example, one commercial Fourier transform instrument uses a helium-neon laser to obtain an accuracy of better than 0.01 cm at 4000cm, whereas older dispersive instruments could have an error of 50 cm The accuracy of... 

Infra-red spectra in the vapour phase are rarely determined with dispersive spectrophotometers unless the substance is a gas at room temperature. Special long-path, airtight gas cells are required. The technique has become more widely used with the advent of Fourier transform infra-red spectrophotometers coupled directly to gas chromato- graphs. 

In recent years, much work has been devoted to the identification and interpretation of infra-red spectra by computer. Collections of spectra on paper can be converted into a numerical form (digitised) and recorded on a disk or tape, and many modem infrared spectrophotometers record the spectra directly in digital form. The use of a data station coupled to an infra-red spectrophotometer enables the spectrum to be matched automatically against those in the library collection, and the names of compounds giving the closest fit displayed. An indication of the closeness of fit may also be given. It is important that the identification is checked by a careful comparison of the spectrum with a printed copy of that of the compound(s) indicated. 

GC-Fourier transform infra-red (GC-FTIR) spectroscopy is less frequently used than GC-MS, but involves a similar principle in which the outlet from the column is coupled to an infra-red spectrophotometer. The technique currently suffers from a lack of library spectra, as the IR spectra taken in the vapour phase can be subtly different from condensed-phase spectra or spectra collected using the well-established KBr disc method. 

Commercial infra-red spectrophotometers cover one or more specific ranges within the above regions, the range defined by the transmission of... 

One of the three spectra labelled Ato C below is produced when ethanal is analysed in an infra-red spectrophotometer ... 

This layer is then analysed directly by internal reflectance infra-red spectroscopy. Since there is no handling of the sample, contamination is reduced to a minimum. However, only infra-red spectral analysis is possible with this system since the material absorbed on the germanium prism is always a mixture of compounds, and since the spectrophotometer used for the production of the spectra is not a high-precision unit, the information coming from this technique is limited. While identification of specific compounds is not usually possible, changes in spectra, which can be related to the time of day, season, or to singular events, can be observed. 

The kinetics of IPN formation were followed by Fourier transform infra-red (FTIR) spectroscopy. For FTIR experiments,the mixture was injected in a cell formed by two NaCl windows separated by a 20 /im thick gasket. The spectra were obtained on a Nicolet 60SX spectrophotometer equipped with a Specac heating chamber with automatic temperature controller. Reaction conversion was calculated from the change of the normalized absorbance of the isocyanate peak at 2275 cm" and C=C peak at 1639 cm. ... 

A 10 cm gas cell was used to record the infra-red spectra of gaseous products. The spectra of chain fragments were measured by casting a thin film from warm toluene on a KCi plate. The spectra of polymer residues were recorded using the KCi disc technique. All spectra were run on a Perkin-Elmer 257 Grating Spectrophotometer. 

Oxidation of Am (III) One aliquot of Am (III) nitrate stock solution was dried under an infra red lamp, and the dry solid was dissolved in a measured volume of the appropriate solution and transferred to the thermostatically-controled spectrophotometric cell. The stability of Am (VI) in organic phases was examined by spectrophotometry by observing the absorption peak of Am (VI) in the region 990-1010 nm. All the spectrophotometric studies were carried out with a Cary 17 spectrophotometer. 

The IR (infra red) spectrum of diosgenin as KBr disc (2mg/200mg) was recorded on a Jasco 5300 FT- IR spectrophotometer to which the IR spectrum was shown in Figure 5. The characteristic bands for diosgenin are shown below. 

Infra-red Spectrum. Attenuated total reflection (ATR) measurements (10) were made using a Perkin Elmer 683 spectrophotometer, to examine the form II and form I bands at 530 and 510 cm respectively. 

Spectrophotometry is one of the most popular modalities of spectroscopies that measure the intensity of transmitted and reflected light. The typical spectral range covered by high-end commercial spans from the near ultra-violet (X 200 nm) to the near infra-red (> 3 pm). This is the reason many use the term UV-VIS to designate spectrophotometry (the technique), or the spectrophotometer (the instrument). 

While diffraction grating based spectrophotometers are a powerful tool to collect transmission and reflection spectra in the UV to near infra-red range of the spectrum, they are not the best choice for measurements in the mid and far infrared range. For measurements in the IR, dispersive instruments are not as efficient or convenient as the Fourier transform (FT) spectrometers. Generally, FT instruments have a higher throughput, better accuracy and precision, compared to grating based instruments. 

Several experimental techniques can be used to study transport phenomena in polymers nuclear magnetic resonance imagiug (NMR), UV spectrophotometer, gas chromatography/flame ionization detector (GCMD), high-performance liquid chromatography (HPLC), laser interferometry, gravimetric method and Fourier Transform Infra-Red spectroscopy (FTIR). 

In infra-red spectroscopy a sample being analysed is irradiated with electromagnetic waves in the infra-red region of the electromagnetic spectrum. The machine used is called a spectrophotometer, and it detects the intensity of the wavelengths of infra-red radiation that passes through the sample. 

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