Theoretical electron impact excitation to the low-lying metastable states of neutral argon

Summary form only given, as follows. Knowledge of rates of metastable levels of neutral argon is important for diagnosing plasmas used in discharges, lighting, laser and plasma processing. In the range of /spl sime/1-100 torr, the level populations of argon obtained from the rates are important for interpreting molecular dissociation fractions based on actinometry. At present, we find major discrepancies between different experimental data and theoretical calculations of the large excitation cross sections to these metastable levels. For instance, the experimentally measured cross sections for the 1s/sub 4/ to the 2p/sub 5/ transition is only one tenth of that generated from a theoretical calculation. We present calculations of these cross sections using several different theoretical approaches ranging from semiempirical to more complex distorted wave with exchange and first-order-many-body methods and make assessments of these different methods. Results are compared with available experimental data including those recently measured at the University of Wisconsin-Madison as well as other theoretical calculations.