title: Observations of interstellar HOCO+:  abundance enhancements toward the galactic center.
abstract: A survey of the 4(04)-3(03) and 1(01)-0(00) transitions of HOCO+ has been made toward several molecular clouds.  The HOCO+ molecule was not observed in any sources except Sgr B2 and Sgr A.  The 5(05)-4(04) and 4(14)-3(13) transitions were also detected toward Sgr B2.  The results indicate that gas phase CO2 is not a major carbon reservoir in typical molecular clouds.  In Sgr B2, the HOCO+ antenna temperature exhibits a peak approximately 2' north of the Sgr B2 central position (Sgr B2[M]) and the 4(04)-3(03) line emission is extended over a approximately 10' x 10' region.  The column density of HOCO+ at the northern peak in Sgr B2 is approximately 3 x 10(14) cm-2, and the fractional abundance relative to H2 > or = 3 x 10(-10), which is about 2 orders of magnitude greater than recent predictions of quiescent cloud ion-molecule chemistry.
authors.affiliation: Five College Radio Astronomy Observatory, University of Massachusetts, USA.
authors.forename: Y C
authors.initials: YC
authors.lastname: Minh
authors.forename: W M
authors.initials: WM
authors.lastname: Irvine
authors.forename: L M
authors.initials: LM
authors.lastname: Ziurys
mesh_terms: D055580:Astronomical Phenomena; D001256:Astronomy; D002245:Carbon Dioxide / Q000032:analysis / Q000737:chemistry*; D055598:Chemical Phenomena; D002621:Chemistry; D005118:Extraterrestrial Environment; D007477:Ions; D013057:Spectrum Analysis
chemical_list: D007477:Ions; D002245:Carbon Dioxide