สำนักราชบัณฑิตยสภา

«“√ “√ √“™∫— ≥±‘ µ¬ ∂“π ªï ∑’Ë Û ©∫— ∫∑’Ë Ù µ.§.-∏.§. ÚıÙ¯ 1131 Scientific Instrumentation in Research IR Spectroscopy in five other areas. First, a general knowledge about principles of organic structures is a must. You should also have an understanding about common functional group. Second, an organized and systematic approach must be applied. Third, understanding of how to interpret a spectral trace is essential. Fourth, appreciating the dangers of using negative or unreliable data to make positive conclusions about a molecular structural feature is important Fifth, being able to maintain a proper perspective in situations where conflicting data sets seem to be in hand is necessary, and when this occurs, being able to draw on experience gained from past success in problem solving is helpful. Finally, simultaneously using data from NMR, MS, IR, UV-VIS and looking repeatedly for multiple pieces of data to support individual conclusions might be considered as a universal goal. Infrared spectroscopy measures the vibrations of molecules. Each functional group, or structural characteristic, of a molecule has a unique vibrational frequency that can be used to determine what functional groups are in a sample. When the effects of all the different functional groups are taken together, the result is a unique molecular “fingerprint” that can be used to confirm the identity of a sample. Butadiene was the essential chemical ingredient of the synthetic rubber program during World War II. Butadiene molecules were linked in long polymer chains to produce synthetic rubber. Knowing the concentration and purity of butadiene was essential to controlling rubber quality, and infrared spectroscopy was the only technique that could accurately gauge these properties. Finding the concentration and purity of hydrocarbons is only the very tip of what infrared spectroscopy can do. Because of its versatility and convenience, IR spectroscopy is now an essential in almost every branch of chemistry. Modern infrared spectrometers are very different from the early dispersive instruments that were introduced in the 1940s. While there is still a need for dual-beam dispersive instruments in high-precision work, most instruments today use a Fourier Transform infrared (FT-IR) system.