## fine structure constant, $$\alpha$$

https://doi.org/10.1351/goldbook.F02389
Atomic fundamental physical constant, α = (µ0/e2)c0.2h = 7.297 353 08 (33) x 10-3, where µ 0 is the permeability of vacuum, e the elementary charge, h the Planck constant, and c0 the speed of light.
Source:
CODATA Bull. 1986, 63, 1 (https://doi.org/10.6028/jres.092.010)