Thickness effects with intrinsically broad absorption lines

Abstract

Thickness effects have been studied extensively, both numerically and analytically, only for the case where the intrinsic absorber cross-section, σ_a, is an elemental

Lorentzian line having the natural Heisenberg width. Thickness effects with σ_a's corresponding to intrinsically (homogeneously or inhomogeneously) broadened lines have hardly not been studied. We report a numerical study of the latter case in which the σ_a's are taken to be single Voigt lines of various Gaussian-width to Heisenberg-width ratios (O ≤ σ/Г_o ≤ 10). We obtain “phase diagrams” showing effectively thin-absorber regions in the plane of intrinsic broadening (σ/Г_o or FWHM of σ_a) versus total absorber thickness (O ≤ t_a ≡ f_an_aσ_o ≤ 10). These diagrams are useful in evaluating when and to what extent spectral distortions from thickness effects need to be taken into account in real situations.