[en] Some new energy levels belonging to the 4f¹⁴6snp³P_0,2 series of neutral ytterbium have been measured by a three-step laser excitation technique. The spectra of the 6snp³P₂ series were analysed with MQDT. It is found that 4f¹³5d²6s³P₂ and ¹D₂ are two perturbers of the 6snp³P₂ series and the admixture coefficients of these perturbers in the bound 6snp³P₂ series were calculated. (author)

[en] Interference of light has been reinvestigated theoretically by linear superposition of two different state-vector functions, of which each describes the photons from one of two different light sources in both polarization and intensity. By the use of microscopic parameters for a photon, namely probability amplitude and phase, it is again validated that interference of light occurs only between the same photons possessing a set of the selfsame eigenvalues

[en] The (5p_3/2 ns)₁ (n = 13 - 21), (5p_3/2 nd)₃ (n = 13 - 24) autoionizing levels of strontium have been measured by the laser multi-step excitation method and polarization technique. In the core excitation profiles for the (5p_3/2 ns)₁ states below the 5p_1/2 ionization limit, the distortions appear at the locations corresponding to the (5p_1/2 ns)₁ and (5p_1/2 nd)₁ levels. Distortions also appear in the (5p_3/2 nd)₃ core excitation profiles. These results show that it exists interseries interactions between the (5p_j ns) and (5p_j nd) autoionizing series of strontium