Connection between the atomic photoeffect and internal conversion

It is shown that over an appreciable energy range $K$-, $L$-, and $M$-shell photoeffect total cross sections are proportional to $E1\mathrm{}$ internal-conversion coefficients from the same subshell. In the nonrelativistic dipole approximation the ratio $\frac{{\beta }^{E1\mathrm{}}}{\sigma }=\left(\frac{3}{8\pi }\right){\left(Z\alpha \right)}^{-2\mathrm{}}$, independent of shell and subshell; numerically, for $s$ waves, this ratio holds to 1 MeV. Screening effects enter only at low energies, reaching several percent at the $K$-shell threshold.