The soft x-ray spectroscopy of solids

Abstract 1. An account is given of new experimental investigations on the radiation emitted from solid elements of the first two groups in the periodic table in the wave-length region 40-500 A. As a result, the properties of these soft X-ray bands have been systematized. The effect of variation of the temperature of the material is also described. 2. The bands reflect the properties of the energy levels of the substance dealt with. A characteristic difference between those of metals and non-metals has been established. The temperature effect on the metal bands is shown to be directly connected with the Maxwellian distribution of the conduction electrons, and the influence of thermal expansion is appreciable. A new feature of the levels of a solid, namely, a large broadening of the valence levels of lowest energy is proposed. With the help of this conception, the general interpretation of the bands is almost complete; they can be used for providing detailed information on the level system in specific cases. In determining the precise features of a band, the crystal structure of the material is the most important factor.