There are several types of excited states that can be relevant in catalysis:
Electronic Excited States: Occur when electrons are promoted to higher energy orbitals. Vibrational Excited States: Involve increased vibrational energy levels within the molecule. Rotational Excited States: Involve changes in the rotational energy levels of molecules. Surface Plasmons: Collective oscillations of electrons at the surface of metal nanoparticles, often induced by light.