# Autoionization state

I am reading this paper: "Role of Autoionizing State in Resonant High-Order Harmonic Generation and Attosecond Pulse Production"

In the paper a transition from the $$\ce{In+}$$ ground state to an autoionization state is discussed:

$$4d^{10}5s^2 \, {}^1\!S_0 \longrightarrow 4d^95s^25p\,(^2\!D)\,{}^1\!P_1$$

I am trying to understand why this is an autoionization state. If I follow the Aufbau principle, an electron in the ground state $$4d^{10}5s^2$$ that is excited should be in the state $$3d^95s^25p$$. If this is just the lowest excited state, why is it considered an autoionization state?

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