there has been a bit of debate about work about whether, in principle, one can halt radioactive decay through use of the quantum zeno effect. The argument goes that you can measure the precise species of, say, an ion through spectroscopy, knowing exactly what element and what isotope it is based on using its fine/hyperfine electronic structure. Thus you know enough quantum numbers to meaningfully know its state, which would be relevant in taking advantage of the effect. The strong conjecture is that you can generally halt particle-emission decays by rapid enough measurements of its state, as a change to its nuclear or electronic structure would be detectable via energy level shifts that your lasers would be tuned to take advantage of (perhaps even a gamma decay could be affected if your apparatus was sensitive and precise enough to tune a laser to the very-super-ultra-fine splitting that would [presumably] be caused by differences in nuclear volume between the excited and relaxed nuclear states). The weak conjecture is that this would only work in something such as 7Be+3, which decays via electron capture and has only one electron, and so the spectroscopy would be directly acting upon a particle actually involved in the decay. Importantly, a distinction is made in this latter case between a change in decay rate due to the Zeno Effect and a change due to changing the electron capture's cross-section via literally just changing where it's spending its time. Additionally, if you could directly address nuclear energy levels and nucleons, would this change anything?
The null conjecture is that this is nonsense, which I'm inclined towards by gut but don't have the quantum theory chops to argue or mathematically demonstrate. feel free to laugh at our brief episode of insanity if none of this makes any sense. also feel free to talk about random cool quantum stuff if any comes to mind