  We present a Berkeley-Illinois-Maryland Association (BIMA) Array molecular
survey of the star forming core ahead of HH 80N, the optically obscured
northern counterpart of the Herbig-Haro objects HH 80/81. Continuum emission at
1.4 mm and 8 micron is detected at the center of the core, which confirms the
presence of an embedded very young stellar object in the core. All detected
molecular species arise in a ring-like structure, which is most clearly traced
by CS(2-1) emission. This molecular ring suggests that strong molecular
depletion occurs in the inner part of the core (at a radius of ~0.1 pc and
densities higher than ~5 x 10^4 cm^{-3}). Despite of the overall morphology and
kinematic similarity between the different species, there is significant
molecular differentiation along the ring-like structure. The analysis of the
chemistry along the core shows that part of this differentiation may be caused
by the UV irradiation of the nearby HH 80N object, that illuminates the part of
the core facing HH 80N, which results in an abundance enhancement of some of
the detected species.
