Absorption & Emission Spectral Lines (2D)

Element

Spectrum mode

Gas Temperature

Temperature (Doppler broadening) 6000 K

Selected Line

Wavelength

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Photon energy

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Transition

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Lines in this element

How it works

Every atom has a ladder of allowed electron energy levels. An electron dropping from a higher level n2 to a lower one n1 emits a photon of exactly one wavelength; the same atom sitting in front of a bright continuous source absorbs that same wavelength out of the beam. For hydrogen this is given exactly by the Rydberg formula 1/λ = R(1/n1² − 1/n2²) with n1 = 2 (the Balmer series, the only hydrogen series that falls in visible light) — this simulator computes those wavelengths live rather than looking them up.

Helium and sodium have more complex, multi-electron energy structures, so their visible lines (including sodium's famous close D1/D2 doublet at 589.0/589.6 nm — the orange glow of a sodium streetlamp) are taken from their real measured spectra instead of a closed-form formula.

Raising the gas temperature increases the atoms' random thermal velocities, and each one's individual Doppler shift smears the line into a slightly wider Gaussian profile (Δλ/λ ∝ √T/m) — heavier sodium atoms broaden far less than light hydrogen at the same temperature. The line width here is scaled up for visibility; the √(T/mass) dependence driving it is the real physics.