Fig. 3.11 — Complex polarisability

Real (solid line) and imaginary (dashed line) parts of the complex atomic polarisability α_e(ω) [Eq. (3.62)] of an atom as a function of the angular frequency ω. ω_R = 10¹⁶ rad/s (corresponding to λ_R = 188 nm) and γ_e = 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.