What is the use of blank in ir spectroscopy?
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As you probably already know, you can use infrared (IR) spectroscopy to determine the structure of a polymer, or other chemical due to characteristic vibrations of chemical bonds. This is a very useful analytical tool, as you might have guessed, but to get useful information, you must perform the technique properly.The first thing you need to do is run a background spectrum. This is so that you only get the data from your sample, and not a spectrum containing the other chemicals which are always present. For example, if your sample is on a substrate, such as a salt plate or a KBr pellet, you need to run a background spectrum of the substrate (glass is not an acceptable IR substrate. Do you know why?). Also, the carbon dioxide and other chemicals in the air also vibrate when hit with IR radiation, and they will show up in your spectrum as well if you do not have a background spectrum. These gaseous chemicals can mostly be eliminated by purging the sample chamber with nitrogen.
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