SENSITIVITY OF INTERSTELLAR CHEMISTRY TO THE RATIO OF THE COSMIC-RAY IONIZATION OF HE AND H$_2$

Author Institution: Department of Physics, The Ohio State University, Columbus, OH 43210, USA; Departments of Physics, Astronomy and Chemistry, The Ohio State University, Columbus, OH 43210, USA; Centre de Recherche Astronomique de Lyon, Ecole Normale Superieure, 46 Allee d'Italie, F-69364 Lyon cedex 7, France