Cross sections for collision processes of Li atoms interacting with electrons, protons, multiply charged ions, and hydrogen molecules

The available experimental and theoretical cross section data for collision processes of Li atoms in the ground state and excited (up to n = 3) states with electrons, protons, and multiply charged ions have been collected and critically assessed. The electron-impact processes include excitation from the ground state, transitions between excited states with n = 2, 3, and ionization from all states considered. The heavy-particle-impact processes include excitation, ionization (for the proton case), and electron removal (the sum of ionization and electron capture). Well-established cross section scaling relationships have been used to generate the cross sections for processes for which no information was found in the literature. This approach was particularly extensively used for the collision processes involving excited Li states, and for collisions with protons and multiply charged ions. In addition, available data for collision processes of Li atoms and ions with neutral hydrogen molecules are shown. The ''recommended'' cross sections for the considered processes, generated either by critical assessment of available data or by a scaling procedure, have been fitted to simple analytic expressions which ensure correct asymptotic behavior of the cross sections. These recommended cross sections are presented by giving their analytic-fit expressions and tabulating the values of the parameters entering these analytic fits. For those reactions from the ground state for which there is a significant amount of cross section information, we also present the recommended cross sections in graphical form together with the cross section data used for their generation. The criteria for assessing the accuracy of the experimental data, theoretical calculations, and procedures used in determining the recommended cross sections are discussed. (C) 1997 Academic Press.