Windows sodium chloride

Infrared spectra were recorded on a Perkin-Elmer Model 521 spectrophotometer and 10-15% (w/v) polymer solutions were used. A pair of Perkin-Elmer solution cells with sodium chloride windows were used to hold the sample solution and reference solvent. 

Most cells used in infrared spectrometry have sodium chloride windows and the path length is likely to vary with use because of corrosion. For quantitative work, therefore, the same cell should be used for samples and standards. In general, quantitative analysis in the infrared region of the spectrum is not practised as widely as in the ultraviolet and visible regions, partly because of the additional care necessary to obtain reliable results and partly because the technique is generally considered to be less sensitive and less precise a precision of 3-8% can be expected. 

Procedure Take about 15-20 mg of sample in a previously cleaned small agate mortar and powder it thoroughly (about 200 mesh). Add to it 2 drops of purified paraffin (commonly known as Nujol) or any other suitable mulling liquid and continue the trituration until a very smooth paste of uniform consistency is achieved. Now, transfer the slurry to a sodium chloride window, placing it carefully into the cavity made by the spacer. Consequently, place the other window on top and thus assemble the cell. With the help of a clean piece of tissue-paper wipe out the excess paste that has squeezed out from the cell windows. Finally, introduce the cell in the respective cell-compartment. 

No satisfactory infrared spectrum of chloromethyldifluorophosphine in the gas phase could be obtained, since the sodium chloride windows of the gas cell were rapidly coated with a white substance. The P-F stretching frequency probably occurs between 900 and 830 cm.-1, where a broad, very strong absorption was... 

The reaction of trans- [Rh(PR3)2Cl(CO)] with methyl iodide was studied by monitoring the IR spectra of solutions of the complex (2 x 10-2 mol L"1) in methyl iodide (redistilled) in a thermostatted solution IR cell provided with sodium chloride windows. A Perkin-Elmer model 577 spectrometer was used. The data was analyzed using the FACSIMILE computer program (14). 

A ceU for combined infrared-ultraviolet spectra devised by Leftin is shown in Fig. 23. The sample is mounted with platinum wire in a rectangular quartz cage which is a close fit in the quartz adsorption cell used to observe the ultraviolet spectrum. The uv cell is sealed directly to a pyrex tube which connects with the IR cell at the other end. Sodium chloride windows are used for measurement of the infrared spectrum. Provision is made for gas admission and evacuation and for heating of the sample by an external furnace. 

Fig. 21. Schematic representation of a subsonic C02 laser with purely chemical excitation (after Cool82)). A He and Fg injectors, H CO2 and NO inlet, C construction detail shown in B, L D2 mixing array, K part of the D2 inlet system which is shown in detail in J, D sodium chloride window, E totally reflecting cavity mirror with long focal length, M, F beam-folding (plane) mirrors, O partially reflecting cavity mirror for output coupling, N laser beam, G resonator housing flushed with nitrogen...

The cells for use in visible and ultraviolet spectrometers are usually cuvets 1 cm thick internal distance between parallel walls), although cells of different pathlengths and volumes can be used. These are illustrated in Figure 16.16. For infrared instruments, various assorted cells are used. The most common is a cell of sodium chloride windows. Fixed-thickness cells are available for these purposes and are the most commonly used. The solvent, of course, must not attack the windows of the cell. Sodium chloride cells must be protected from atmospheric moisture (stored in desiccators) and moist solvents. They require periodic polishing to remove fogging due to moisture contamination. Silver chloride windows are often used for wet samples or aqueous solutions. These are soft and wUl gradually darken due to exposure to visible light. 

The purity of the compound is best confirmed by an elemental analysis for sulfur and nitrogen. If the sum of the sulfur and nitrogen percent compositions is less than 100, this strongly suggests that oxygen impurity is present.2 15 The infrared spectrum of (SN)X can be measured on a thin film sublimed4 onto a sodium chloride window. Principal absorption maxima in the 600-1200 cm-1 region are 620-625(w), 670(vs), 720-840(, broad), and 995(s) cm-1. 

NaNOj A spurious band at 1355 cm", along with a weaker but sharper band at 836 cm", was traced to a deposit of sodium nitrate on a sodium chloride window near a Nernst glower. The deposit was attributed to the reaction of nitric acid with the window, the nitric acid originating from nitric oxide produced by direct union of nitrogen and oxygen at ca. 1900°C on the Nernst glower. 

Na2SiF(, Silicon tetrafluoride attacks a sodium chloride window forming sodium silicofluoride. 

The high wavenumber limit for fundamental vibration absorption is 4000 cm (HF absorbs at 3958 cm ). The low wavenumber limit is more variable, as it changes with instrumental and cell transmission limitations. If sodium chloride windows are used, the low wavenumber limit is about 650 cm The correlation charts for this region (4000-600 cm ) are shown in Fig. 13.3(a-f). Major group frequencies below 600 cm" such as C—Br and C—I stretch and aromatic out-of-plane ring bend, to name some, have been covered in the text. 

Figure 6.1 Acrylonitrile-butadiene-styrene terpolymer (Novodur W - Bayer Chemicals), benzene solution evaporated on sodium chloride windows. Source Author s own files)...

Infrared detectors are similar in construction to those used in UV detection. The main difference is that the sample cell windows are constructed of sodium chloride, potassium bromide, or calcium fluoride. A limitation of this type of detector is caused by the low transparency of many useful solvents (Skoog et al., 1998). Recent changes to interface systems that use spraying to induce rapid evaporation of the solvent provide good sensitivity and enhanced spectral quality (LaCourse, 2000). 

Effect of Light on the Decomposition of Silver Chloride. Introduce 2 ml of a 0.1 W silver nitrate solution into a test tube and add dropwise such an amount of a saturated sodium chloride solution that will be sufficient for the complete precipitation of the silver as -a chloride. Rapidly filter out the precipitate, rinse it with water and put it on two watch glasses. Place one glass with the precipitate in a dark cupboard, and leave the other at a window in daylight. In an hour, compare the colour of the precipitates and explain the phenom->ena you observe. How does light affect the reaction After the experiment, put the precipitates containing a silver compound into he jars set aside for them. 

Gather these materials Two pie pans filled with water 2 teaspoons sodium chloride (NaCl) silver nitrate (AgN03) 1 package of index cards a red light bulb and some coins, buttons, keys, or leaves. You will need a dark closet in which to work or a room where you can cover the windows and make it dark. 

Chlorine trifluoride gradually attacks the silver chloride windows of the infrared cell. When the attack is sufficient to cause serious background on the infrared scan, the cell windows are polished best by using a 5% sodium thiosulfate solution on a velvet polishing cloth. 

Beryllium. Beryllium is a light, silvery white metal, which can be made by electrolysis of a fused mixture of beryllium chloride, BeClg, and sodium chloride. The metal is used for making windows for X-ray tubes (X-rays readily penetrate elements with low atomic number, and beryllium metal has the best mechanical properties of the very light elements). It is also used as a constituent of special alloys. About 2% of beryllium in copper produces a hard alloy especially suited for use in springs. 

Infrared, like the UV and visible regions of the spectrum, provides a useful method for detecting solutes in liquid streams. The detector uses the principle of attenuated total reflectance, with a single beam spectrometer being used in conjunction with a tow volume flow cell. The cell is equipped with sodium chloride, calcium fluoride or zinc selenide windows and can be heated to temperatures greater than 100°C. The detector can... 

The most widely used window materials (Table 3) are alkali halides, particularly sodium chloride and potassium bromide. 

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