Can Nonradiative Decay occur for a single atom?

[Higgy]

As I understand it, "nonradiative decay" of a system from an excited state to a lower-energy state is any type of decay that does not result in the emission of an electron.

I can't think of any way that a free atom could decay without emitting a photon. Molecules, yes, (through vibration/rotation), but atoms - no. Is that true?

[DrDu]

As I understand it, "nonradiative decay" of a system from an excited state to a lower-energy state is any type of decay that does not result in the emission of an electron.
You certainly mean photon, not electron.

I can't think of any way that a free atom could decay without emitting a photon. Molecules, yes, (through vibration/rotation), but atoms - no. Is that true?

Yes, although radiationless transitions are already observed in quite small molecules like e.g. Benzene.

[Higgy]

You certainly mean photon, not electron.

Sorry, yes - photon. (What a strange, plasma-filled world we'd live in otherwise!)

Yes, although radiationless transitions are already observed in quite small molecules like e.g. Benzene.

Great, thank you.

[Ygggdrasil]

What about dynamic quenching mechanisms, for example Förster resonance energy transfer or Dexter electron transfer, that transfer the energy of the excited state to an interacting molecule? Could these mechanisms provide a nonradiative pathway for an excited state atom to decay to the ground state?

[SpectraCat]

What about dynamic quenching mechanisms, for example Förster resonance energy transfer or Dexter electron transfer, that transfer the energy of the excited state to an interacting molecule? Could these mechanisms provide a nonradiative pathway for an excited state atom to decay to the ground state?

Yes, but the OP specified a free atom, which I took to mean that a non-interacting atom. In that case, spontaneous emission of radiation is the only available decay mechanism.