Guide for users of data resources

This chapter addresses the problem of where to find reliable numerical values for collision cross sections (or the equivalent) as functions of energy. There are several variables that define specific data requirements: identity of the collision partners, collision energy, reaction channel. Thus, electrons or photons colliding with atoms, molecules, and ions and nonreactive collisions of atoms and ions with other atoms and ions (so-called heavy particle collisions) are all possibilities. Resulting processes include elastic scattering, excitation, ionization, dissociation, recombination, and charge exchange. For many combinations of these variables, no measurements or calculations have been reported. In those cases, only new measurements or calculations (or estimations based on similar systems and circumstances) can provide the data. 25 refs., 5 tabs