A recent breakthrough in the analysis of Nd IV resulted in the establishment of 37 energy levels of the ground configuration 4f3. We report here the completion to all 41 levels of this configuration. Wavelength measurements extended to 2800 Å and in higher excitation conditions lead to the classification of 1426 lines involving the excited configurations 4f25d, 4f26p, 4f26s. Owing to configuration mixing between 5p64f26p and the core-excited 5p54f4, numerous 5p64f25d–5p54f4 transitions, normally dipole-forbidden, are observed. Altogether 111 odd parity levels and 121 even parity ones have been established. Their parametric least-squares fits have rms deviations of 91 cm−1 and 37 cm−1, respectively. The interaction 5p64f25d–5p54f35d has an impact on the 4f3–4f25d transition probabilities computed by means of the Cowan codes. Theoretical values of lifetimes are reported for all the even parity levels.
The spectrum of neodymium excited by a sliding spark source was photographed on two vacuum ultraviolet normal-incidence spectrographs. About 250 lines attributed to Nd V, hitherto unknown, have been identified. The analysis of this spectrum established all the energy levels of the configurations 4f2, 4f5d, 4f6s and 4f6p (except for 4f2 1S0). Altogether, 48 known levels classify about 160 lines. Their theoretical calculation includes a least-squares fit with an rms error of 28 cm−1 for the even-parity levels and 26 cm−1 for the odd-parity ones, as well as the best values for relevant radial interaction parameters. In particular, interactions with the core-excited configurations 5p54f3 and 5p54f25d are discussed. Intensities derived from phosphor image plates are used to estimate an effective temperature in the spark of Teff=3.6 eV.
The Ag II spectrum emitted from hollow cathode discharges has been recorded in the region 940^8500 Ð with Fourier transform and high dispersion photographic instruments. 311 lines have been classi¢ed and measured at high accuracy (AE0.03^0.003 cm À1 above 2000 Ð, AE0.002^0.0005 Ð in the VUV region). Improved energy level values have been derived from the lines, and 24 new odd levels have been found. The level structure has been interpreted by ab initio and parametric calculations.
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