energiataso

Energiataso, meaning energy level in Finnish, is a discrete allowed value of energy that a system can possess in quantum mechanics. For atoms and molecules, this concept describes the quantized energies of electrons or other charged particles. Energy levels arise from the solutions to the Schrödinger equation for a given potential; in atoms, they are often labeled by principal quantum number n and, in multi-electron atoms, by angular momentum and other quantum numbers. The levels are not continuous; between them lie energy gaps. The ground state corresponds to the lowest energy level, with excited states at higher energies.

In atoms, electron energy levels lead to characteristic spectra: photons with energies equal to differences between levels are absorbed or emitted, hν = |E_i − E_f|. Selection rules determine which transitions are allowed. The distribution of electrons among levels at a given temperature follows the Boltzmann distribution, with higher levels less populated, and degeneracy factors playing a role.

In solids, the concept extends to energy bands. Individual atomic levels broaden into bands due to interactions between atoms; the valence band and conduction band determine electrical conductivity. The band gap is the energy difference between the top of the valence band and the bottom of the conduction band. Doping and temperature influence the position of the Fermi level and carrier populations.

In nanoscale systems such as quantum dots, energy levels become discrete due to spatial confinement, resembling atomic-like spectra. Energiataso is central in spectroscopy, photonics, semiconductor physics, and chemistry, where it is used to describe electronic structure, optical transitions, and reaction energetics. Common terms include HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) in chemistry contexts.