Rydberg constant for spectral lines

rydberg is the Rydberg constant, which sets the characteristic wavenumber scale of hydrogen spectral transitions.

Use

It appears in the Rydberg formula for wavelengths of hydrogen-like atoms. Combine it with speedOfLight to relate wavenumber to frequency and planckConstant to relate frequency to photon energy.

Caveats

Use the appropriate reduced-mass correction for real nuclei when precision matters. Wavenumber is inverse length, not frequency; use divide with consistent SI units.