Knowledge Bank

In 1951 Simon published a paper on Spectroscopy in the Infrared by Reflection and computed the reflecting power of an absorbing medium, both for light polarized parallel to and light polarized perpendicular to the plane of incidence. Two angles of incidence were chosen, with a wide range of values of index of absorption and refractive index. However, the full practical possibilities of the technique were not realized at the time and it was not until 1961 that Fahrenfort published his first paper on the use of ATR to obtain infrared spectra. This publication aroused great interest since new sampling techniques for the infrared region are few and far between. Since 1961 a great deal of ingenuity has gone into the design of expensive devices to exploit ATR techniques. The theoretical aspects of ATR are now re-examined and it is concluded that some of the more complicated and expensive designs of attachment give little advantage over simpler types. Micro ATR and multi-reflection ATR systems are also considered and their uses and limitations discussed.