Electronic Absorption Spectroscopy: Theory and Practice

Abstract

Of the wide variety of spectroscopic techniques available to the modern spectroscopist, electronic absorption spectroscopy has perhaps the longest history, effectively tracing its origins back to the original work of Bunsen and Kirchoff on the spectroscopy of atomic species in flames. Consequently, the technique was responsible for the rapid expansion of the periodic table in the mid to late nineteenth century and, more importantly, for the development and testing of theories of atomic and molecular electronic structure in the early twentieth century. As a technique with a long history, it would be expected that electronic absorption spectroscopy would be widely used. This is true. However, we must contrast the use of electronic absorption spectroscopy with that of infrared and NMR techniques. While the latter are widely used in a qualitative sense, the former finds most use in quantitative measurements. This contrast is discussed briefly below. First, however, some basic theory needs to be considered.