Sample pellet is cloudy. Insufficient evacuation time or leaky seals. Check seals on the die and lengthen evacuation period. Sample pellet is clear at first but quickly becomes cloudy. Damp powder or damp atmosphere. Dry the KBr powder or sample, check seals on the die and lengthen evacuation period. Joachim Weiss. Request further information. Related products. We provide evacuable pellet press dies made of hardened stainless steel for the preparation of high-quality pellets with diameters between 5 mm - 40 mm.
The press dies come with all necessary Our robust manual hydraulic laboratory presses with 15 and 25 t load configurations are essential for producing KBr pellets and the preparation of XRF samples. They have been in the market for decades Atlas is a power assisted hydraulic press and is available in three version for compressive loads up to 8 t, 15 t and 25 t. The press is designed as a table-top unit and operates hydraulically. Related questions What does infrared spectroscopy measure?
What does infrared spectrum show in an IR? How does infrared absorption spectroscopy work? What is Fourier Transform infrared spectroscopy? How does infrared spectroscopy aid in criminal investigations? How is infrared spectroscopy used to identify the presence of organic compounds in water samples? How does infrared spectroscopy identify functional groups? Why are NaCl plates used instead of quartz plates in IR spectroscopy to load sample?
What does infrared spectroscopy tell you? How might infrared spectroscopy be useful in pharmacy? This method exploits the property that alkali halides become plastic when subjected to pressure and form a sheet that is transparent in the infrared region.
Potassium bromide KBr is the commonest alkali halide used in the pellets. Cesium iodide CsI may also be used to measure the infrared spectrum in the to cm -1 low-wavenumber region. The preparation method for 13 mm-diameter pellets is described below. Approximately 0. A force of approximately 8 tons is applied under a vacuum of several mm Hg for several minutes form transparent pellets.
Degassing is performed to eliminate air and moisture from the KBr powder. Inadequate vacuum may result in easily broken pellets that scatter light. Before forming the KBr powder into pellets, pulverize it to mesh max. Note that rapid heating can oxidize some of the KBr powder to KBrO 3 , causing a brown discoloration.
After drying the powder, store it in a desiccator. When performing measurements, the background can be measured with an empty pellet holder inserted into the sample chamber.
However, background measurements on a pellet holder with a pellet of KBr only, that contains no sample, can correct for infrared light scattering losses in the pellet and for moisture adsorbed on the KBr. This is a method for measuring powder samples with simple sample pretreatment. The sample is distributed in a liquid of approximately equal refractive index, and the infrared spectrum is measured. Generally, the powder is dispersed in non-volatile liquid paraffin Nujol that has low absorption in the infrared region.
To prepare a sample, pulverize approximately 10 mg sample powder in a mortar and pestle.
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