The high resolution subvalence d-shell absorption spectrum of zinc I

The absorption spectrum of atomic zinc due to transitions from the first subvalence d-shell has been reinvestigated at high resolution using synchrotron radiation as the background source. The data on the six series converging onto the inverted doublet of the first excited state of zinc II (3d94s22D3/2,5/2) have been extended to higher n-values. The splitting of the leading members of the f-series converging towards the lower limit (3d94s2(2D5/2) nf a, b) is observed for the first time (n=4: (5.7±1)cm-1). The experimental data is analysed using two different theoretical approaches. The overall consistency of the data is analysed using a six-channel two-limit MQDT model. As a consequence, the value of the energy of the 2D5/2-limit is revised to be (138,493.7±1) cm-1. The second approach consists of Slater-Condon type calculations for the 3d94s2 np (n=4,...,9) configurations. Three different methods for calculating energy levels are presented: (a) numerical diagonalisation of d2p energy matrix in the appropriate coupling scheme and fitting of relevant parameters to experimental level energies. (b) the Shortley and Fried method [1, 2] (c) analytical formulae in jcK-coupling with fitting as under (a). It is shown that method (c), which is easily handled, offers sufficient accuracy for the configuration 3d94s2 np (n>4). (orig.)