R. K. Janev and D. Reiter, Phys. Plasmas 9, 4071 (2002); see also: R. K. Janev and D. Reiter: ``Collision processes of hydrocarbon species in hydrogen plasmas: I. The methane family'', Report FZ-Jülich Jül -3966, Forschungszentrum Jülich, Jülich Germany (Feb. 2002) ISSN 0944-2952. Copies may be ordered from: Forschungszentrum Jülich GmbH, Zentralbibliotek, D-52425 Jülich, Germany.