Elektronspektrum

Elektronspektrum refers to the distribution of electron energies within a material. When atoms or molecules interact, their individual electron energy levels combine and broaden, forming bands of allowed energies. These bands are separated by forbidden energy gaps where electrons cannot exist. The specific arrangement and width of these electron energy bands, along with the gaps between them, determine the material's electrical and optical properties.

In solids, the uppermost filled energy band is called the valence band, and the next higher empty band is called the conduction band. The energy difference between the top of the valence band and the bottom of the conduction band is known as the band gap. In conductors, the valence and conduction bands overlap or are very close, allowing electrons to move freely and conduct electricity. In semiconductors, there is a small to moderate band gap, meaning that under certain conditions, such as an increase in temperature or the absorption of light, electrons can be excited into the conduction band, enabling conductivity. Insulators have a large band gap, requiring a significant amount of energy to excite electrons into the conduction band, thus they are poor conductors of electricity. The study of elektronspektrum is fundamental to understanding solid-state physics and material science.