New levels of Ta II with energies higher than 72,000 cm−1

- We report the discovery of 14 even energy levels of the first ion of Tantalum (Ta II).
- Their energy ranges from 72,000 to 81,000 cm−1.
- For comparison, up to now only even levels between 0 and 44,000 cm−1 were known.
- These levels belong to up to now unknown electron configurations.
- With help of these levels, approximately 100 spectral lines of Ta II can be classified.

We studied the hyperfine structure of Tantalum lines appearing in a high-resolution Fourier transform spectrum. Hundreds of lines of Ta in this spectrum are still unclassified; most of them, especially in the UV region, belong to Ta II. When investigating such lines we found 14 new levels of Ta II. These new levels are the highest-lying known Ta II levels and do not belong to the already known configurations.