Although it is only a proposal, here is an example from 2011 involving thorium. Note that the term "gamma-ray" in this context refers to the nuclear origin of the ray rather than its frequency. In this case the gamma-ray has a frequency in the optical range. Also notice that the thorium isomer is located within a compound of Lithium.
Proposed gamma-ray laser could emit 'nuclear light' http://phys.org/news/2011-05-gamma-ray-laser-emit-nuclear.html Harry On Thu, Jan 21, 2016 at 7:07 PM, Eric Walker <eric.wal...@gmail.com> wrote: > I wrote: > > I did not intend the earlier description to preclude the possibility of >> some kind of electromagnetic stimulation coming along and nudging the >> isomer out of its excited level into a lower one. I'd be interested if >> someone knows of something like this. >> > > In the paper that Harry linked to [1], there was mention at the end of a > claim in 1999 of being able to stimulate the 2.4 MeV decay of hafnium-178m2 > with x-rays with less than 100 keV. This is a controversial result, for > the energy needed to stimulate the transition is very low, and the result > hasn't been confirmed yet. > > Eric > > > [1] http://epubs.surrey.ac.uk/469/1/fulltext.pdf > >
