Theoretical investigation of spectroscopic properties of W25+

Energy levels and emission spectra of W²⁵⁺ ion have been studied by performing the large-scale relativistic configuration interaction calculations. Configuration interaction strength is used to determine the configurations exhibiting the largest influence on the 4f³, 4d⁹4f⁴, 4f²5s, 4f²5p, 4f²5d, 4f²5f, 4f²5g, and 4f²6g configuration energies. It is shown that correlation effects are crucial for 4f²5s→4f³ transition which in a single-configuration approach occurs due to the weak electric octupole transitions. As well, the correlation effects affect 4f²5d→4f³ transitions by increasing transition probabilities by an order. The corona model has been used to estimate the contribution of various transitions to the emission in a low-density electron beam ion trap (EBIT) plasma. Modeling in 10-30 nm wavelength range produces lines which do not form emission bands and can be observed in EBIT plasma.