The spectrum of Mo V was observed in the wavelength region from 250 to 6000 Å, using a variety of spectrographs and light sources. The level system was revised and extended to include all but one of the levels of 4d2, 4d5s, 4d5d, 4d6s, 4d5p, 4d6p, 4d4f and 5s5p. Hartree-Fock calculations were made and also parametric least-squares calculations including configuration interaction. Scaling factors between Hartree-Fock and least-squares values for the interaction integrals were obtained and used for an isoelectronic comparison. The ionization potential was estimated to be 54.49 ± 0.02 eV.

We discuss recent work on reaction-diffusion processes that take place on complex networks. The inherent inhomogeneity of the substrate leads to a series of new phenomena, which bear only a small resemblance to the classical results of the field. The annihilation rate is abnormally high in such systems, while at the same time depletion zones are absent in the A + A → 0 reaction and no segregation is observed for the A + B → 0 reaction. These results are mainly attributed to the presence of network hubs and to the small network diameter of such systems.

The spectrum of Nb IV was observed with a sliding spark in the region from 430-3000 Å on the 6.5 m normal incidence vacuum spectrograph and the 3.4 m Jarrell-Ash spectrograph at the Zeeman-Laboratorium. About 294 lines were observed. The level system (ground configuration 4d2, isoelectronic with Sr I) was revised and extended to include 4d nl with nl = 4d, 5s, 5p, 5d, 4f, 6s and 6p respectively and 5s5p. Parametric calculations were made for the even and the odd level system taking into account the configuration interaction directly. The ionization energy was estimated to be 37.73 eV, from the position of the 4d5s and 4d6s configurations.

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Two different proposals for the identification of the 4d105p6 1S0 level in Xe III are examined using the methods of optical spectroscopy. The proposal by Hertz [Z. Phys. A274, 289 (1975)] is confirmed. The 5p6 1S0 level is located 210 857.55 cm-1 above the Xe III ground state.