Light Sources with General Application

Abstract

The light sources initially used in spectroscopy were tungsten lamps or more generally glowing solids and gas-discharge lamps. The emission of glowing solids is based on Planck’s and Kirchhoff’s law, whereas in gas-discharge lamps the radiation from characteristic transitions of valence electrons is used as well. Thus, in the latter a high density of radiation can be obtained in a narrow frequency range. Recently, the broad-band radiation emitted from synchrotron sources has been increasingly employed in various fields of spectroscopy. On the other hand, the rapid development of various types of lasers, particularly those relying on emission from semiconductor diodes, has opened up many new spectroscopic techniques such as laser ultraviolet or far-infrared applications, frequency tuning, or sub-picosecond resolution spectroscopy.