Figure 3.11 — Complex polarisability Figure 3.11 — Complex polarisability. Real (solid line) and imaginary (dashed line) parts of the complex atomic polarisability αe(ω) [Eq. (3.62)] of an atom as a function of the angular frequency ω. ωR = 1016 rad/s (corresponding to λR = 188 nm) and γe = 1015 rad/s. The order of magnitude of these values is realistic even though they do not correspond to any specific atom. Note that the frequency axis is logarithmic.