SIMBAD references

This paper summarizes the most recent knowledge concerning normal and three-body association ion-molecule reactions between small hydrocarbon ions (C_mH⁺_n; m=1-6, n=0-9) and the neutral reactants H and H₂. Selected radiative association reaction rate coefficients have been calculated and estimated based on three-body laboratory results. Some of the normal and radiative association rate coefficients have been incorporated into our ``new standard'' model of dense cloud interstellar chemistry. We find that atomic H provides an insufficiently appreciated mechanism to increase the level of saturation of C_mH⁺_n ions, with m>3 in dense interstellar clouds despite the fact that the H/H₂ abundance ratio is only 10^–4. New model results show in particular that a significant abundance of the basic aromatic cyclic molecule benzene (c-C₆H₆) can now be produced in dense clouds.Subject headings: