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A capital R with an infinity subscript, the hydrogen spectrum scale.
Also known as: Rydberg constant, R infinity, Rydberg
The Rydberg constant sets the wavelengths of hydrogen's spectral lines. Its infinity subscript is not decoration: it marks the idealised case of an infinitely heavy nucleus, and the real hydrogen value differs slightly because the proton also moves.
Denotes the Rydberg constant for an infinitely heavy nucleus, setting the scale of atomic spectral wavelengths.
Contexts: Laboratory
Carries an infinity subscript because it assumes a stationary nucleus; the value for actual hydrogen is reduced by the electron-to-proton mass ratio.
Contexts: Laboratory
Is among the most precisely measured constants in physics, which is why it anchors tests of quantum electrodynamics.
Contexts: Laboratory
An italic capital letter R with a small sideways figure-eight set below and to the right.