APEX telescope observations of new molecular ions
  Hydrides are key ingredients of interstellar chemistry since they are the
initial products of chemical networks that lead to the formation of more
complex molecules. The fundamental rotational transitions of light hydrides
fall into the submillimeter wavelength range. Using the APEX telescope, we
observed the long sought hydrides SH+ and OH+ in absorption against the strong
continuum source Sagittarius B2(M). Both, absorption from Galactic center gas
as well as from diffuse clouds in intervening spiral arms over a large velocity
range is observed. The detected absorption of a continuous velocity range on
the line of sight shows these hydrides to be an abundant component of diffuse
clouds. In addition, we used the strongest submillimeter dust continuum sources
in the inner Galaxy to serve as background candles for a systematic census of
these hydrides in diffuse clouds and massive star forming regions of our Galaxy
and initial results of this survey are presented.
