SPECTROSCOPY OF HIGHLY EXCITED-LEVELS IN NA II-IV IONS

The structures of many high-lying levels of the type 2p(5) 4f in Na II , 2p(4) 5g in Na III and 2p(3) 6h in Na IV are suggested by comparing results of beam-foil spectroscopic studies and calculations based on M CDF formalism. Relative excitation functions of these levels show simi lar behaviour to those of low-lying levels of ions in the correspondin g charge state. The lifetimes of these high-lying levels are determine d and compared with theoretical predictions and previously measured va lues wherever possible. Measurement of lifetimes of several such level s are reported for the first time.