New Constraints on Diffuse Interstellar Cloud Models. The Model of the ζ Ophiuchi Cloud Revisited

Using most recent observational data as well as new experimental and theoretical determinations of various reaction rate coefficients, we present a model of the ζ θphiuchus cloud. the radiative transfer equation is solved in a plane parallel geometry taking into account absorptions by both the gas and by dust. A part certain atypical molecules (CH+, CN) and neutral iron, we are able to reproduce the observed column densities of neutral atoms, and molecular species, including the rotational populations of molecular Hydrogen with a two shell model. the concentrations of other simple molecules are predicted.