Experimental and ab initio studies of the reactive processes in gas phase i-C3H7Br and i-C3H7OH collisions with potassium ions.

Collisions between potassium ions and neutral i-C₃H₇Br and i-C₃H₇OH, all in their electronic ground state, have been studied in the 0.10-10.00 eV center of mass (CM) collision energy range, using the radiofrequency-guided ion beam technique. In K⁺ + i-C₃H₇Br collisions KHBr⁺ formation was observed and quantified, while the analogous KH₂O⁺ formation in K⁺ + i-C₃H₇OH was hardly detected. Moreover, formation of the ion-molecule adducts and their decomposition leading to C₃H₇ + and either KBr or KOH, respectively, have been observed. For all these processes, absolute cross-sections were measured as a function of the CM collision energy. Ab initio structure calculations at the MP2 level have given information about the potential energy surfaces (PESs) involved. In these, different stationary points have been characterized using the reaction coordinate method, their connectivity being ensured by using the intrinsic-reaction-coordinate method. From the measured excitation function for KHBr⁺ formation the corresponding thermal rate constant at 303 K has been calculated. The topology of the calculated PESs allows an interpretation of the main features of the reaction dynamics of both systems, and in particular evidence the important role played by the potential energy wells in controlling the reactivity for the different reaction channels. [ABSTRACT FROM AUTHOR]