CmHn+ Reactions with H and H2: An Experimental Study

We report measurements of the reactions of a number of hydrocarbon ions with atomic and molecular hydrogen made using a selected ion flow tube (SIFT) operating at room temperature. Results, including branching ratios and rate coefficients, are reported for C m H n + ions ( m = 2−6, n = 0−9). Highly unsaturated hydrocarbon ions undergo mainly H atom abstraction reactions with H 2 forming C m H n +1 + + H products. More saturated ions are unreactive. Two types of reactions occur for H atoms: H atom transfer to give C m H n - 1 + + H 2 (if exothermic) and association (to give C m H n +1 + ).