Effects of collision energy and vibrational excitation of CH cations on its reactivity with hydrocarbons: But-2-yne CHCCCH as reagent partner.

The methyl carbocation is ubiquitous in gaseous environments, such as planetary ionospheres, cometary comae, and the interstellar medium, as well as combustion systems and plasma setups for technological applications. Here we report on a joint experimental and theoretical study on the mechanism of the reaction CH + CHCCCH (but-2-yne, also known as dimethylacetylene), by combining guided ion beam mass spectrometry experiments with ab initio calculations of the potential energy hypersurface. Such a reaction is relevant in understanding the chemical evolution of Saturn's largest satellite, Titan.

The Selective Role of Long-Range Forces in the Stereodynamics of Ion-Molecule Reactions: The He +Methyl Formate Case From Guided-Ion-Beam Experiments.

Long-range intermolecular forces play a crucial role in controlling the outcome of ion-molecule chemical reactions, such as those determining the disappearance of organic or inorganic "complex" molecules recently detected in various regions of the interstellar medium due to collisions with abundant interstellar atomic ions (e.g. H and He ).

Experimental investigation of the reaction of helium ions with dimethyl ether: stereodynamics of the dissociative charge exchange process.

The fate of dimethyl ether (DME, CHOCH) in collisions with He ions is of high relevance for astrochemical models aimed at reproducing the abundances of complex organic molecules in the interstellar medium. Here we report an investigation on the reaction of He ions with DME carried out using a Guided Ion Beam Mass Spectrometer (GIB-MS), which allows the measurement of reactive cross-sections and branching ratios (BRs) as a function of the collision energy. We obtain insights into the dissociative charge (electron) exchange mechanism by investigating the nature of the non-adiabatic transitions between the relevant potential energy surfaces (PESs) in an improved Landau-Zener approach.