hydrogenserien

Hydrogenserien refers to groups of spectral lines in hydrogen that arise when an electron transitions from a higher energy level n2 to a fixed lower level n1. Each series is defined by its lower level, with n1 = 1 giving the Lyman series (ultraviolet), n1 = 2 the Balmer series (visible), n1 = 3 the Paschen series (infrared), n1 = 4 the Brackett series (infrared), n1 = 5 the Pfund series (infrared), and n1 = 6 the Humphreys series (infrared), among others. The lines converge to a series limit as n2 increases without bound.

The lines can be described by the Rydberg formula for hydrogen: 1/λ = R∞ (1/n1^2 − 1/n2^2), where R∞ is the Rydberg constant (approximately 1.0973731568508×10^7 m−1). In emission, n2 > n1; in absorption, electrons are excited to n2 and drop to n1. The hydrogenserien reflect the quantized nature of atomic energy levels predicted by quantum theory, with energy levels E_n = −13.6 eV / n^2 in the simple Bohr model.

Historically, the Balmer series (n1 = 2) was described empirically in 1885, the Lyman series (n1 = 1) identified in 1906, and later quantum mechanics provided a full explanation of the series as transitions between discrete energy levels.

The hydrogenserien are fundamental in spectroscopy and astrophysics, enabling measurements of composition, temperature, density, and motion in astronomical objects, and serving as essential tools in laboratory spectroscopy and calibration.