In this critical compilation, all experimental data on the spectrum of neutral carbon known to us were methodically evaluated and supplemented by parametric calculations with Cowan’s codes. The sources of experimental data vary from laboratory to astrophysical objects, and employ different instrumentations, from classical grating and Fourier transform spectrometers to precise laser spectroscopy setups and various other modern techniques. This comprehensive evaluation provides accurate atomic data on energy levels and wavelengths (observed and Ritz) with their estimated uncertainties, as well as a uniform description of the observed line intensities. In total, 412 previously known energy levels were optimized with the help of 1221 selected best-observed lines participating in 1365 transitions in the wavelength region 750 Å–609.14 μm. The list of recommended energy levels is extended by including 21 additional levels found through quantum-defect extrapolations or parametric calculations with Cowan’s codes. In addition, 737 possibly observable transitions are predicted. Critically evaluated transition probabilities for 1616 lines are provided, of which 241 are new. With accurate energy levels obtained, combined with additional observed data on high Rydberg states, the ionization limit was determined to be 90820.348(9) cm⁻¹ or 11.2602880(11) eV, in fair agreement with the previously recommended value, but more accurate.

All available experimental data on the spectrum of singly ionized carbon have been critically analyzed. Measurement uncertainties of all published studies have been reassessed. The scope of observational data includes laboratory emission spectra of arcs, sparks, electrodeless discharges, and hollow cathode lamps recorded with grating and Fourier transform spectrometers, laboratory photoabsorption spectra, and emission spectra of planetary nebulae. The total number of observed spectral lines included in this compilation is 597. These lines participate in 972 transitions. From this list of identified transitions, we have derived a set of 414 energy levels, which are optimized using a least-squares fitting procedure. The identifications are supported by parametric calculations with Cowan’s codes. The existing tables of critically evaluated transition probabilities have been extended with our newly calculated data. The ionization energy has been derived from the newly optimized energy levels with improved precision. Data on the isotope shifts and hyperfine structure have also been compiled.

Laser-produced Sn plasma sources are used to generate extreme ultraviolet light in state-of-the-art nanolithography. An ultraviolet and optical spectrum is measured from a droplet-based laser-produced Sn plasma, with a spectrograph covering the range 200–800 nm. This spectrum contains hundreds of spectral lines from lowly charged tin ions ${\mathrm{Sn}}^{1+}-{\mathrm{Sn}}^{4+}$ of which a major fraction was hitherto unidentified. We present and identify a selected class of lines belonging to the quasi-one-electron, Ag-like ([Kr]$4d^{10}nl$ electronic configuration), ${\mathrm{Sn}}^{3+}$ ion, linking the optical lines to a specific charge state by means of a masking technique. These line identifications are made with iterative guidance from cowan code calculations. Of the 53 lines attributed to ${\mathrm{Sn}}^{3+}$, some 20 were identified from previously known energy levels, and 33 lines are used to determine previously unknown level energies of 13 electronic configurations, i.e., $7p$, $(7,8)d$, $(5,6)f$, (6–8)$g$, (6–8)$h$, $(7,8)i$. The consistency of the level energy determination is verified by the quantum-defect scaling procedure. The ionization limit of ${\mathrm{Sn}}^{3+}$ is confirmed and refined to 328 908.4 ${\mathrm{cm}}^{-1}$, with an uncertainty of 2.1 ${\mathrm{cm}}^{-1}$. The relativistic Fock-space coupled-cluster (FSCC) calculations of the measured level energies are generally in good agreement with experiment but fail to reproduce the anomalous behavior of the $5d{}^{2}D$ and $nf{}^{2}F$ terms. By combining the strengths of the FSCC calculations, cowan code calculations, and configuration interaction many-body perturbation theory, this behavior is shown to arise from interactions with doubly excited configurations.

We have measured the stopping powers and straggling of fast, highly ionized atoms passing through thin bilayer targets made up of metals and insulators. We were surprised to find that the energy losses as well as the straggling depend on the ordering of the target and have small but significantly different values on bilayer reversal. We ascribe this newly found difference in energy loss to the surface energy loss field effect due to the differing surface wake fields as the beam exits the target in the two cases. This finding is validated with experiments using several different projectiles, velocities, and bilayer targets. Both partners of the diatomic molecular ions also display similar results. A comparison of the energy loss results with those of previous theoretical predictions for the surface wake potential for fast ions in solids supports the existence of a self-wake.