So whats happening is a high speed polymerization reaction initiated by the action of laser light. An infrared beam moniters the amount of unreacted acrylate double bonds. But what is an acrylate double bond? Am I correct in saying that a double bond absorbs IR radiation? The double bond is the bond between a CH2 and a CH, in the paper that I am reading. My next question is, why use Fourier Transform Infrared spectroscopy over any other spectroscopic technique to determine the amount of unreacted double bonds through time in a sample?