Isotope shift studies in UV lines of Sm I on FTS: level isotope shifts and configuration assignments of the energy levels of neutral samarium atom

Isotope shifts in 200 spectral lines of neutral samarium atom (Sm I) in the region of 355-455 nm (28160-21970 cm^-1) have been measured using a Fourier Transform Spectrometer. Isotope shift data in 187 spectral lines of Sm I are being reported for the first time. Level isotope shifts, of 119 high odd- and 7 low even-parity energy levels have been evaluated using present isotope shift data combined with the earlier available data. These values have enabled us to check the assignments to 4f ⁶6s6p and 4f ⁵5d6s ² configurations of the odd-parity levels made earlier on the basis of parametric calculations. For several levels, the reported compositions of the mixed configuration of type [4f ⁵(⁶H⁰, ⁶F⁰) 5d6s ² + 4f ⁶(⁷F) 6s6p(³P⁰)] have been interpreted with the help of our values. 20 unassigned energy levels have been uniquely assigned to 4f ⁵5d6s ² configuration. The present study provides values of the levels, which were tentatively assigned to 4f ⁵5d ²6s and 4f ⁶5d6p configurations. We could also identify 4f ⁶5d6p configuration for 12 unassigned levels.Received: 16 December 2004, Published online: 7 September 2004PACS: 31.30.Gs Hyperfine interactions and isotope effects, Jahn-Teller effect