Simple hydrogen-bearing molecules in translucent molecular clouds
  We demonstrate relations between column densities of simple molecules: CH, CH$^{+}$, H$_{2}$ and OH. The H$_{2}$, CH and OH molecules seem to occupy the same environments because of tight relations between their column densities. In contrary to this CH$^{+}$ column density does not correlate with those of other simple molecules. 
T. Weselak, J. Kre{\l}owski
astro-ph.GA