Continuum interaction in low-energy radiationless transitions

L-shell Coster-Kronig transition rates are calculated for Ar through a formulation which includes the effects of final-state channel mixing. The interchannel interaction changes individual transition rates by as much as 84%. The relative term intensities from the present calculation agree better with experiment than calculations which do not include channel mixing. The discrepancies previously found between measured and calculated total $L_1$-$L_2$,3${\mathrm{M}}_1$ Coster-Kronig transition rates and the ratios of $L_1$-$L_2$,3${\mathrm{M}}_1$ to $L_1$-$L_2$,3${\mathrm{M}}_2$,3 and $L_1$-$L_2$,3${\mathrm{M}}_1$ ${(\mathrm{}}^1$ ${\mathrm{P}}_1$ ) to $L_1$-$L_2$,3${\mathrm{M}}_1$ ${(\mathrm{}}^3$ ${\mathrm{P}}_1$ ) intensities are largely removed when effects of channel coupling are taken into consideration.