Laboratory measurements of the recombination of PAH ions with electrons: implications for the PAH charge state in interstellar clouds

Dissociative recombination and mutual neutralization of heavier molecular ions: C10H8(+), WF5(+), and C(n)F(m)(+)

Dissociative recombination (DR) rate coefficients for the naphthalene cation, C10H8(+), and WF5(+), and mutual neutralization (MN) rate coefficients for these species and five CnFm(+) ions, were determined at 300 K using variable electron and neutral density attachment mass spectrometry (VENDAMS). DR proceeds at 9 ± 3 × 10(-7) cm(3) s(-1) for C10H8(+) and at 6.1 ± 1.4 × 10(-7) cm(3) s(-1) for WF5(+). Consistent with previous results, MN for the polyatomic cations with the halide anions Cl(-), Br(-), and I(-) exhibits an approximate μ(-1/2) reduced mass dependence of the reactant partners, demonstrating that ion collision velocities influence the rate coefficients. This work is an extension of VENDAMS to systems, where low reactant concentrations are necessary to avoid significant reaction of product ions with the neutral precursor, i.e., conditions not suitable for traditional flowing afterglow measurements, as well as to ions of masses > ∼ 100 Da, which are not amenable to the study of DR in magnetic storage rings. Our results expand the sparse literature on DR and MN of heavier ions.