Atomic Origins of EUV Light

In Section 4.2 we will show that EUV emission from multiply excited states of Sn multiply charged ions, and not the aforementioned singly excited states of type 4p⁵4d^m+1 and 4d^m–14f, is in fact the dominant contribution to the overall atomic opacity in 1-μm wavelength Nd:YAG-laser-produced tin plasma. Following up on these conclusions, valid for dense plasma near local thermodynamic equilibrium (LTE), we conclude in Section 4.3 that the electronic population of ions also in lower-density, non-LTE plasmas, such as those produced in industry using 10-μm wavelength CO₂ lasers, can be well described by thermal, single-temperature distributions. Section 4.4 explores the influence of optical depth defined as the spatial integration over the product of the plasma’s opacity and mass density. Concluding remarks are presented in Section 4.5.