D. P. RUFFLE, R. TERZIEVA, E. HERBST, Departments of Physics and Astronomy, and Chemical Physics Program, The Ohio State University, Columbus, OH 43210.
It has recently been proposed that C7- is a carrier of five of the numerous diffuse interstellar bands. In this talk, we report an attempt to reproduce the required abundance of C7- relative to hydrogen of 4 × 10-8 through the use of various models for the chemistry in diffuse clouds. Our models incorporate large neutral and charged linear hydrocarbons, and contain the time-dependent desorption of seed molecules from grain surfaces. We are able to find conditions that lead to the production of the required fractional abundance of C7- but only for short periods of time in an astronomical sense.