Rydberg constant

The Rydberg constant, often denoted as R&infin;, originally defined empirically in terms of the spectrum of hydrogen, is given a theoretical value by the Bohr theory of the atom as:
 * $$R_{\infty} = \frac{m_ee^4}{4\pi \hbar^3 c}\ \left( {\mu_0 c^2}{4 \pi}\right)^2 \ . $$