DEUTERATED AMMONIA IN SAGITTARIUS B2

The 85.927 GHz J = 1(11) --> 1(01) transition of deuterated ammonia (N H2D) has been detected in the northern ''hot-core'' in Sagittarius B2 with the BIMA millimeter-wave interferometer. Emission and absorption in the (3, 3) inversion transition of the (NH3)-N-15 isotope has also been detected from the same region with the VLA. The (NH3)-N-15, obser vations confirm the large NH3 abundance enhancements previously inferr ed. The abundance of NH2D relative to NH3 is enhanced by more than an order of magnitude compared to the local elemental (D/H) ratio, but is an order of magnitude lower than in hot-core regions outside the Gala ctic center. The NH2D and NH3 enhancements are consistent with models in which the molecules are formed on dust grains in an earlier, cooler epoch; the comparatively small NH2D enhancement can be explained by t he relatively high temperatures in Galactic center giant molecular clo uds. The difference in physical conditions between Galactic center and local molecular clouds must be considered in deriving the elemental ( D/H) ratio from observations of deuterated molecules.