Autler–Townes effect of autoionization transition at laser separation of lutetium isotopes

The splitting of the transition from a discrete to an autoionization state, used in a three-step photoionization scheme of lutetium $5d6s^2$ $^2D_{3/2}$–$5d6s6p{}^4F^\circ_{5/2}$–$5d6s7s {}^4D_{3/2}$–($53375$cm$^{-1}$)$^\circ_{1/2}$ has been studied. The splitting is proportional to the square root of the intensity, which corresponds to the Autler–Townes effect.