Th. A. M. van Kleef

SPECTRAL STRUCTURE OF NEUTRAL AND IONIZED OSMIUM

In this paper the results of an analysis of all data available on the Os I and Os II spectra are communicated. Of a total number of 263 Os I levels 155 could be interpreted in terms of the quantum theory. The ground level system is associated with the electron configurations 5d66s2 and 5d76s, which are strongly intermingled. Of the 5d8-configuration, however, no trace has been found. In the odd system most levels could be assigned to multiplets of the configurations 5d66s6p, 5d56s26p and 5d76p. Many of the high even states have been attributed to the configurations 5d66s7s, 5d56s27s and 5d66s6d. The number of classified Os I lines is about 40% of the total number known. For the ionization potential of the Os-atom a value of (8.5 ± 0.1) V has been found. As regards Os II, the main progress in the analysis was the definite establishment of 5d56s2 6S52 and the identification of 5d56s(7S)6p 8P92, 72, 52. Approximately 15% of all known Os II lines above 2000 A have been classified. Complete tables energy levels of Os I and Os II with observed J-and g-values and quantum assignments are presented in this paper. Complete tables of classified wavelengths, observed Zeeman effects, a.s.o. have been published elsewhere.

Analysis of 4d 9 -4d 8 5p transitions in Sb vii and Te viii and the ionization limits of Sb vi and Te vii

The spectra of antimony and tellurium have been photographed in the region 625–100 A on 6.60 and 10.7 m spectrographs. The sources used were a sliding spark and a triggered spark. On the basis of these measurements the earlier analyses of these spectra hve been revised and extended. Parametric least-squares-fit calculations and Hartree-Fock calculations were carried out for the 4d9 and 4d8 5p configurations. Comparison of these parameter values has been made for the spectra Ag iii to Te viii. The spectra of Sb vi and Te vii below 300 A were extended and the ionization limits for Sb vi and Te vii have been found to be 795 340(8000) cm−1 or 98.6(1.0) eV and 1 000 900(10 000) cm−1 or 124.0(1.2) eV, respectively.

SPECTRAL STRUCTURE OF DOUBLY AND TREBLY IONIZED HAFNIUM

Abstract A level scheme is presented which accounts for more than 80% of the observed Hf III lines. All levels in the low even group and the odd group have been given quantum assignments. The configurations involved are 5 d 2 , 5 d 6 s , 6 s 2 , 5 d 6 p and 6 s 6 p with 5 d 2 3 F 2 being the ground state of the ion. The only predicted level which could not be located, is 5 d 2 1 S 0 . Some assignments have been made also in the high even system of levels, where fragments of 5 d 7 s and 5 d 6 d have been detected. The ionization potential of Hf III is found to be 23.3 V. The fundamental levels of Hf IV have been established. They leave unexplained most of the lines attributed to that spectrum, but account for the strongest and most characteristics ones. The ionization potential derived for Hf IV is 33.3 V. The structure of the two spectra is discussed in connection with related systems.

A 6.650 m vacuum spectrograph

SummaryThe construction of a 6.650 m in plane Eagle-mounting vacuum spectrograph is described. A concave grating (blaze angle of 5°10′) with 1200 lines a mm is used. The plateholder can rotate around the slit by means of a system of levers. The platechamber volume is separated from the main vacuumchamber by means of a rectangular separation valve. Optical adjustment is very critical and well reproducible. Various lightsources have been used. Several spectra have been photographed and measured. Some of the results are briefly discussed.

Zeeman effect measurements in neutral and singly ionized mercury

Synopsis In this paper the g-values of a number of levels in the Hg I and Hg II spectra are communicated. Complete tables of the observed Zeeman patterns are given. The Paschen-Back effect of the levels 6 1D2 and 6 3D1 in Hg I has been studied. The experimental data are in agreement with the theoretically expected ones, within experimental error.

The ground state of the terbium atom

Abstract From the optical spectrum of free Tb atoms and the Zeeman effect of a few transitions it is proven that the ground state is 4f96s2 6H015/2, which is at 285.580 K below 4f85d6s2 8G13/2, the lowest state known previously.

Revised and Extended Analyses of Se V and Br VI

The spectra of Se V and Br VI were photographed in the 2000 A-200 A and 1200 A-200 A regions on a variety of spectrographs using a triggered spark light source. The new observations have lead to revision and extension of earlier analyses. The 4s2, 4s4p, 4p2, 4s4d, 4s5s and 4s5p configurations have been confirmed in both Se V and Br VI. In addition, the 4s5d and 4s6s configurations have been established in Se V. Fifty-three lines have been classified in Se V and forty-nine lines have been classified in Br VI.

Ninth spectrum of iodine:l ix

The spectrum of iodine was observed in the region 300–80 A on a 10.7-m grazing-incidence spectrograph. The source used was a triggered spark. The earlier analysis of I ix has been revised and extended. Parametric level-fitting calculations support the analysis. Forty-three lines have been classified in this spectrum.

Structure and zeeman effect in the spectrrum of the iridium atom, Ir I

Synopsis The analysis of existing wavelength data of the Ir I spectrum has resulted in the detection of 1 even ground level and 20 odd levels in addition to those reported by previous investigators. Moreover a group of 12 high even levels has been discovered. The total number of classified lines is now 2110, corresponding to 2192 transitions between 30 even ground levels, 164 odd levels and 41 high even levels. The Zeeman effect has been investigated in the wavelength region 2300 — 6000 . For 905 lines the splitting has been observed; of these 296 show resolved patterns. Accordingly, the g-values of practically all levels could be determined and used in the quantum interpretation of the spectrum. The low even terms belong to the electron configurations 5d76s2, 5d86s and 5d9; the odd levels could be associated with the configurations 5d76s6p, 5d86p and 5d66s26p; the high even levels have been assigned to the configurations 5d76s7s, 5d76s6d and 5d66s27s. By means of these identifications an ionization potential of (9.1 ± 0.1) V was derived.

Eleventh spectrum of cesium: Cs xi

The spectrum of cesium has been photographed in the 300–80-A region on a 10.7-m grazing-incidence spectrograph using a triggered spark source. The lowest configuration in Cs xi is 4d9, and its 2D splitting has been found to be 19268 cm−1. Thirty-four levels of the 4d8 5p configuration have been established on the basis of their transitions to the 4d9 2D levels in the 135–115-A wavelength region. Parametric-level fitting calculations support the analysis. Forty-seven lines are now classified in this spectrum.