MehrElektronenFall

MehrElektronenFall is a concept in nanoscale physics describing a cascade of relaxation or transition events that occurs when more than one electron occupies a localized electronic system, such as a quantum dot, a single-molecule junction, or a nanowire segment. The addition of extra electrons enhances Coulomb interactions and increases the density of accessible excited states, enabling a sequence of transitions that relax the system toward its ground state.

Mechanism: In a multi-electron quantum dot, higher-energy configurations can relax via electron-electron scattering, phonon coupling, or photon emission. An initial relaxation can open new lower-energy channels for other electrons, producing a chain of cascaded transitions sometimes referred to as a relaxation cascade or Auger-like process in nanoscale systems. The precise pathways depend on the level structure, coupling to leads, and temperature.

Observables and relevance: MEF can manifest as stepwise changes or kinks in current as a function of bias or gate voltage, as well as multiple emission lines in spectroscopy corresponding to successive transitions. Time-resolved measurements may show a sequence of decay events with characteristic lifetimes. The concept is related to and sometimes overlapping with Coulomb blockade, Hund-like correlations in few-electron dots, and Auger recombination in semiconductors.

Status: MehrElektronenFall is a descriptive label used in some German-language literature to discuss multi-electron relaxation cascades. It is not a universally standardized term and remains a topic of theoretical modeling and targeted experiments in quantum dots and molecular electronics.