  We present an experimental and theoretical study of the emission and
absorption spectra of the Ba$^{+}$ ions and Ba$^{+\ast}$He excimer
quasimolecules in the cryogenic Ba--He plasma. We observe several new spectral
features in the emission spectrum which we assign to the electronic transitions
between bound states of the excimer correlating to the 6$^{2}P_{3/2}$ and
5$^{2}D_{3/2,5/2}$ states of Ba$^{+}$. The resulting Ba$^{+}$(5$^{2}D_{J}$)He
is a metastable electronically excited complex with orbital angular momentum
$L$=2, thus expanding the family of known metal--helium quasimolecules. It
might be suitable for high-resolution spectroscopic studies and for the search
for new polyatomic exciplex structures.
