Rydberg constant

The Rydberg constant, often denoted as R_∞, originally defined empirically in terms of the spectrum of hydrogen, is given a theoretical value by the Bohr theory of the atom as:

$R_{\infty }={\frac {m_{e}e^{4}}{4\pi \hbar ^{3}c}}\ \left({\frac {\mu _{0}c^{2}}{4\pi }}\right)^{2}\ .$

The best value (in 2005) was:

R_∞/(hc) = 10 973 731.568 525 (8) m⁻¹,

where h = Planck's constant and c = speed of light in vacuum.