  It is known from ensemble measurements that rubidium atoms trapped in solid
parahydrogen have favorable properties for quantum sensing of magnetic fields.
To use a single rubidium atom as a quantum sensor requires a technique capable
of efficiently measuring the internal state of a single atom, such as
laser-induced fluorescence. In this work we search for laser-induced
fluorescence from ensembles of rubidium atoms trapped in solid parahydrogen
and, separately, in solid neon. In parahydrogen we find no evidence of
fluorescence over the range explored, and place upper limits on the radiative
branching ratio. In neon, we observe laser induced fluorescence, measure the
spectrum of the emitted light, and measure the excited state lifetime in the
matrix. Bleaching of atoms from the excitation light is also reported.
