| Abstract: | The doubly-charged ion mass spectra of some hydrocarbons, including a variety of structural types, have been obtained by a new technique in which doubly-charged ions are charge exchanged with neutral molecules and so separated from singly-charged ions. The spectra show strong similarities, independent of hydrocarbon structure; characteristic ions include [CmH2]++ (m = 2 to 5), [CnH6]++(n > 6), [C10H8]++, [C12H8]++, [C11H10]++, [C7H7]++·, [C9H7]++· and [C13H11]++·. The fragmentation pattern of 2-phenylnaphthalene has been reconstructed, based on observed reactions of metastable doubly-charged ions to give fragment doubly-charged ions. In addition, we examined metastable ion fragmentations leading to two singly-charged ions for some of the characteristic ions, using several compounds. The value of doubly-charged ion mass spectra of hydrocarbons appears to lie in the information they provide on ion structures; this information was sufficient to permit the proposal of structures for the major ions encountered in this study. |
