Experimental investigation of gaseous ionic structures of interstellar importance: HCO+ and HOC+

Collision-induced dissociation (CID) fragmentation patterns for ions originating from different precursors are consistent with two structures for m/z 29 (HCO+ and HOC+). These results are in agreement with the predictions of recent ab initio calculations which indicate that two stable structures should be experimentally observable. The structure of protonated CO formed by the reaction between H3+ and CO was investigated since it has been suggested that both HCO+ and HOC+ are formed. The experimental data indicates that the product is predominantly the most stable isomer, HCO+; however, 6 +/- 5% of the less stable HOC+ isomer is produced