Ionelectron

Ionelectron is a term occasionally used in atomic and plasma physics to denote a single bound electron associated with an atomic nucleus in a one-electron ion (hydrogen-like ion). In practice, it refers to the simplest bound-electron system where the electron moves primarily in the Coulomb field of the nuclear core. Hydrogen-like ions include He+, Li2+, Be3+, and heavier species with only one electron remaining. The energy spectrum of the ion is predominantly hydrogenic, with energy levels approximately E_n = -Z^2 R_H / n^2, where Z is the nuclear charge and R_H is the Rydberg constant. Real systems show refinements from fine structure, quantum electrodynamics (Lamb shift), and, for multi-electron cores, quantum-defect corrections that depart from the pure hydrogenic model.

Formation and observations: Ionelectrons are probed via spectroscopy, photoionization, and electron-ion recombination experiments. Transitions between bound n-levels yield lines whose wavelengths scale with Z and n, enabling determinations of ion charge state, electron temperature, and field effects. In astrophysical and laboratory plasmas, one-electron ions serve as benchmarks for atomic data used in plasma modeling.

See also: hydrogen-like ion, bound state, quantum defect, Lamb shift, spectroscopic line.