Observations of high-n transitions in the spectra of near-neon-like copper ions from laser-produced plasmas

Spectra in the 7.50-8.70 Å range from highly charged copper ions are analysed, and line identifications are made for the Na-, Ne-, F- and O-like charge states. The spectra are recorded with a spherically bent crystal spectrometer using either a mica or quartz crystal for moderate (λ/Δλ = 3000) and high (λ/Δλ = 8000) energy resolution, respectively. The plasmas from which the spectra are emitted are formed with either a Nd:glass (15 ns pulse) or a XeCl (12 ns pulse) laser. Systematic variations in the observed spectra with pulse energy are studied. Using different laser energies, and defocusing of the laser to reduce the intensity, we create plasmas with different ionization state distributions, which allows us to deconvolve blended lines from different copper ions. Line identifications are made based on relativistic atomic structure calculations that account for configuration interaction in level energies and transition rates. We use full kinetics simulations of ion emissivities, not just calculations of theoretical transition energies, to identify the strong and weak lines in crowded spectral regions. We identify 2p- n ℓ transitions for Ne-like Cu 19+ for 4⩽ n ⩽8 and 2s- n p transitions for 4⩽ n ⩽6. We offer the first identification of high- n ( n ⩽8) Na-like satellites to Ne-like Rydberg resonance lines. The first and second ionization energies for Cu 19+ are found, at 1689.02 and 1709.16 eV, respectively, based on our observations.