Atomic structure considerations for the low-temperature opacity of Sn

作者：Colgan J^*; Kilcrease D P; Abdallah J Jr; Sherrill M E; Fontes C J; Hakel P; Armstrong G S J

来源：High Energy Density Physics, 2017, 23: 133-137.

DOI：10.1016/j.hedp.2017.03.009

We have begun a preliminary investigation into the opacity of Sn at low temperatures (< 50 eV). The emissivity and opacity of Sn is a crucial factor in determining the utility of Sn in EUV lithography, with numerous industrial implications. To this end, we have been exploring the accuracy of some approximations used in opacity models for the relevant ion stages of Sn (neutral through similar to 18 times ionized). We find that the use of intermediate-coupling, as compared to full configuration-interaction, is not adequate to obtain accurate line positions of the important bound-bound transitions in Sn. One requires full configuration-interaction to properly describe the strong mixing between the various n = 4 sub-shells that give rise to the Delta n = 0 transitions that dominate the opacity spectrum at low temperatures. Since calculations that include full configuration-interaction for large numbers of configurations quickly become computationally prohibitive, we have explored hybrid calculations, in which full configuration-interaction is retained for the most important transitions, while intermediate-coupling is employed for all other transitions. After extensive exploration of the atomic structure properties, local-thermodynamic-equilibrium (LTE) opacities are generated using the ATOMIC code at selected temperatures and densities and compared to experiment.

• 出版日期2017-6
• 单位Los Alamos