Taking into account the empirically found b constant that reduced (or "screened") the nucleus charge, Bohr's formula for K α α transitions becomes E = h ν ν = E i − − E f = m e q e 4 8 h 2 ε ε 0 2 ( 1 1 2 − − 1 2 2 ) ( Z − − 1 ) 2 ≈ ≈ 3 4 ( Z − − 1 ) 2 × × 13.6 e V . Dividing both sides by h to convert to the frequency units, one obtains ν ν = E h = m e q e 4 8 h 3 ε ε 0 2 3 4 ( Z − − 1 ) 2 ≈ ≈ ( Z − − 1 ) 2 × × ( 2.47 ⋅ ⋅ 10 15 H z ) .