We have measured the isotope shifts of the 5d to 6p transitions in 134-138Ba II, of which the 5d3/2 to 6p1/2 transition has not been measured earlier. We have also obtained values with improved accuracy of the magnetic dipole and electric quadrupole hyperfine coupling constants of the 6p 2Po1/2,3/2 levels in 135,137Ba II. The measurements are performed in the red and orange parts of the optical spectrum using fast ion beam-laser spectroscopy with an improved procedure which avoids calibration of the ion velocity. A comparison with theory is made.

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The vacuum ultraviolet (VUV) and ultraviolet (UV) emissions of gaseous mixtures of argon with a small amount of nitrogen were investigated in the afterglow of a pulsed transverse discharge. The time dependences of the intensity of the VUV argon continuum at 126.0 nm, the UV nitrogen molecular band at 337.0 nm, and the VUV nitrogen atomic lines at 149.47 and 174.52 nm were analysed in the total pressure range 150–600 hPa and the range 0.125–1.5 hPa of the admixture concentrations. The results show that all these emissions have a common source of excitation energy, namely the atomic metastable 3P2 state of argon. However, atomic nitrogen also receives energy from the atomic 3P1 state of argon and from the excited Ar2* (1u) molecules.

The Xe VI1 and Xe VI11 spectra have been investigated by collision-based spectroscopy. The radiation emitted following electron capture by 1Oq keV Xe4+ ions (q = 6-8) impinging on a He (Ar) gas target has, with some exceptions, been recorded in the 350-8000 (1200-2500)A wavelength region. The xenon ions were provided by the Uppsala University ECR ion source. Many of the observed, previously unreported spectral lines have been identified. In total, nine new energy levels of Xe VI1 and Xe VI11 have been established, of which two are tentative. The analysis was supported by Hartree-Fock calculations.

We have utilized collision-based spectroscopy to investigate the spectra of Xe V and Xe VI. The radiation emitted following electron capture by 50 keV Xe5+ and 60 keV Xe6+ ions impinging on a He (Ar) gas target has been recorded in the 350–6000 (1200–2500) Å wavelength region. A number of new energy levels of Xe V and Xe VI have been established from lines identified by us. In particular, we have observed and identified transitions from the 5s25p4f (5s24f) configuration of Xe V (Xe VI). The analysis was supported by Hartree–Fock calculations.