Contributions to the force multiplier (F_M) as a function of the element atomic number (26 for Fe). A 135 000 K blackbody (dashed line) and below 230 Å totally cut blackbody (Nphot = 0 between 100 and 230 Å) with the same temperature (solid line) were used as radiators, and the force multiplier was calculated at log(ξ) = 2.5 and log(t) = −1.84. The y-axis has a logarithmic scale.