Joseph Reader

Energy Levels of Iron, Fe I Through Fe XXVI

Abstract : This is a revision of the compilation of energy levels of iron of all ionization stages made in 1975 by Reader and Sugar. New material has since been provided for all but two of these ions. The present compilation includes electron configurations, energy levels, term designations, calculated leading percentages for most ions, experimental g-values, and ionization energies. (Author)

Ground Levels and Ionization Potentials for Lanthanide and Actinide Atoms and Ions

Values of the first four ionization potentials of the lanthanides (Z=57–71) and of Hf have been compiled. All except the value for neutral Hf are based on spectroscopic data. The spectroscopic designations of the ground levels of the neutral through triply ionized atoms (Z=57–72) are also tabulated. A similar compilation for the actinides (Z=89–103) lists Sugars recent values for the first ionization potentials through No (Z=102). Accurate spectroscopic ionization potentials have been determined for only two of the actinide ions (Ac+ and Th3+). The ground‐level designations for the neutral through triply ionized actinides are given where they are known or can be predicted with near certainty. A selection of references to the most complete and most recent work on the analyses of the optical spectra of the neutral through triply ionized lanthanide and actinide elements is included.

Wavelengths of spectral lines in mercury pencil lamps.

The wavelengths of 19 spectral lines in the region 253-579 nm emitted by Hg pencil-type lamps were measured by Fourier-transform spectroscopy. Precise calibration of the spectra was obtained with wavelengths of (198)Hg as external standards. Our recommended values should be useful aswavelength-calibration standards for moderate-resolution spectrometers at an uncertainty level of 0.0001 nm.

Ionization energies of doubly and triply ionized rare earths

Values for the ionization energies of the doubly and triply ionized rare earth atoms have been derived from interpolated spectroscopic properties of the 4fNns series, and from interpolated energy intervals relating the first series member, 4fN6s, to the ground state. The results in eV are La III19.1774(6)Tb III21.91(10)IV 39.79(20)Ce20.198(3)IV 36.758(5)Dy22.79(30)41.47(20)Pr21.624(3)38.98(2)Ho22.84(10)42.48(32)Nd22.14(30)40.41(20)Er22.74(10)42.65(21)Pm22.32(36)41.09(32)Tm23.68(10)42.69(20)Sm23.43(30)41.37(38)Yb25.03(2)43.74(20)Eu24.70(32)42.65(32)Lu20.9596(10)45.19(2)Gd20.63(10)44.01(35)Hf33.33(2) The values for the doubly ionized atoms agree to within ∼ 1% with those deduced from thermodynamic measurements on lanthanide oxides. A value for the ionization energy of Gd II of 12.09(8) eV was determined by using new spectroscopic data for Gd II and Gd III.

Spectra of Rb ii, Sr iii, Y iv, Zr v, Nb vi, and Mo vii in the Vacuum Ultraviolet

The characteristic resonance-line spectrum in the Kr i isoelectronic sequence, consisting of the five transitions to the 4p6 1S0 ground state from levels with J = 1 in the 4p54d and 5s configurations has been observed from Rb ii to Mo vii. The observations were made with sliding sparks, on the 10.6-m normal-incidence spectrograph at NBS and the 5-m grazing-incidence spectrograph in Lund. A number of transitions from higher levels of the type 4p5nd, 4p5ns, and 4s4p65p were also observed. Isoelectronic comparisons are given for all observed levels. The ionization energies in electron volts are Rb ii 27.285Y iv 60.60Nb vi 102.06Sr iii 42.87Zr v 80.36Mo vii 125.66.Anomalous relative intensities observed for the 4p54d transitions are found to be caused by excitation conditions within the light source.

Optimizing Czerny–Turner Spectrographs: A Comparison between Analytic Theory and Ray Tracing

The analytic theory of aberrations has been used to derive an expression for the magnitude of the coma width of the image in the meridional plane in a Czerny–Turner spectrograph with unequal mirror radii. The calculated properties of a 4-m spectrograph with equal radii and a recently constructed 3.34-m spectrograph with unequal radii are compared with the results obtained by tracing individual rays. The agreement is excellent, in contrast to the results of Chandler [ J. Opt. Soc. Am.58, 895 ( 1968)]. The lateral position of the grating for complete elimination of coma found experimentally with the 3.34-m instrument is in fair agreement with the theory. A correction to the 3 longitudinal grating position is given for a Czerny–Turner spectrograph which results in a flatter focal surface.

EUV spectra of highly-charged ions W54+?W63+ relevant to ITER diagnostics

We report the first measurements and detailed analysis of extreme ultraviolet (EUV) spectra (4–20 nm) of highly-charged tungsten ions W54+ to W63+ obtained with an electron beam ion trap (EBIT). Collisional-radiative modelling is used to identify strong electric-dipole and magnetic-dipole transitions in all ionization stages. These lines can be used for impurity transport studies and temperature diagnostics in fusion reactors, such as ITER. Identifications of prominent lines from several W ions are confirmed by the measurement of isoelectronic EUV spectra of Hf, Ta and Au. We also discuss the importance of charge-exchange recombination for the correct description of ionization balance in the EBIT plasma.

Mercury in the HgMn stars chi Lupi and HR 7775

Observations of mercury lines in the HgMn stars chi Lupi and HR 7775 made with the Hubble Space Telescope Goddard High Resolution Spectrograph are presented and analyzed. In chi Lupi we find that all observed lines are consistent with the same isotopic mixture (essentially pure (204)Hg). Strong ionization anomalies are present, with UV Hg I lines being too weak and Hg III lines too strong for the abundance derived from lines of the majority ionization state, Hg rr. Observations of mercury in I;IR 7775 show less extreme isotope and ionization anomalies. We find that the ionization anomaly in the Hg I resonance lines can be plausibly explained as a non-LTE effect, but the same non-LTE calculations show that the Hg III ionization anomaly in chi Lupi cannot be explained in this way. Radiative force calculations show that the observed mercury abundance cannot be supported in the atmosphere by the radiative forces alone. We suggest that weak mixing brings mercury into the line-forming region from below the photosphere, while a wind of order 10(-14) M. yr(-1) supports a cloud of Hg III at very small optical depths. (Less)

3s–3p, 3p–3d, and 3d–4f transitions of sodiumlike ions

New measurements have been made for wavelengths of the 3s–3p, 3p–3d, and 3d–4f transitions of the sodiumlike ions Cu18+, Zn19+, Ga20+, Ge21+, As22+, Se23+, Br24+, Kr25+, Y28+, Zr29+, Nb30+, Mo31+, Ru33+, Rh34+, Pd35+, Ag36+, and Sn39+. The measurements were made by photographing laser-produced plasmas and tokamak plasmas with grazing-incidence spectrographs. The energies of the transitions were also calculated with Dirac–Fock computer codes. By fitting the differences between the observed and calculated wave numbers to simple formulas, least-squares-fitted wavelengths for all sodiumlike ions from Ar7+ to Xe43+ were determined. The estimated uncertainty of the fitted wavelengths is ±0.007 A, which makes them useful as reference values. The wavelengths range from 9 to 713 A.

The Copper Isoelectronic Sequence: Ba27+-W45+

The spectra of the copper-like ions Ba27+, La28+, Nd31+, Sm33+, Gd35+, Dy37+, Er39+, Yb41+, Ta44+, and W45+ have been observed with a laser-produced plasma and a 2.2 m grazing incidence spectrograph. Wave-lengths, energy levels, and ionization energies are presented for each of these ions.