In 2003, Kuan and coworkers reported the detection of interstellar glycine (NH 2 CH 2 COOH ) based on observations of 27 lines in 19 different spectral bands in one or more of the sources Sgr B2(N-LMH ), Orion KL, and W51 e1/e2. They supported their detection report with rotational temperature diagrams for all three sources. In this paper we present essential criteria that can be used in a straightforward analysis technique to confirm the identity of an interstellar asymmetric rotor such as glycine. We use new laboratory measurements of glycine as a basis for applying this analysis technique, both to our previously unpublished 12 m telescope data and to the previously published Swedish-ESO Submillimetre Telescope (SEST) data of Nummelin and colleagues. We conclude that key lines necessary for an interstellar glycine identification have not yet been found. We identify some common molecular candidates that should be examined further as more likely carriers of several of the lines reported as glycine. Finally, we illustrate that a rotational temperature diagram used without the support of correct spectroscopic assignments is not a reliable tool for the identification of interstellar molecules.

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We previously reported the spectral detection of the first interstellar sugar, which is known as glycolaldehyde (CH 2 OHCHO), by observing six separate millimeter-wave rotational transitions with the NRAO 12 m telescope while pointed toward the Sagittarius B2 North hot core source known as the Large Molecule Heimat (LMH) source. In the present BIMA array work, we have spatially mapped Sgr B2 using the 8 08-7 17 transition of glycolaldehyde at 82.4 GHz. We find that glycolaldehyde has a spatial scale of ≥60Љ unlike its isomers methyl formate and acetic acid, which are concentrated in the LMH source that has a spatial scale of ≤5Љ. We estimate that the relative abundance ratios of (acetic acid) : (glycolaldehyde) : (methyl formate) are ∼1 : 0.5 : 26 within the LMH source. It is likely that the conditions of the LMH source favor the chemically reactive nature of glycolaldehyde over its isomers and other large molecules such as dimethyl ether. The ensuing chemistry leads to glycolaldehyde destruction in the LMH source and glycolaldehyde survival outside of the LMH source in extended cloud extremities. This scenario is supported by comparison of line widths, which shows that glycolaldehyde possesses a factor of 2-3 greater line width than those of other complex molecules that are confined largely to the LMH source.