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We have studied the beam-foil spectra of phosphorus between 600 and 2 200 Å and measured radiative lifetimes for 21 excited terms in P I-P V. We discuss the merits of several methods for evaluating the decay constants and compare the results with theoretical transition probabilities as well as with recent experimental studies of oscillator strengths in the P I, Si I, Al I, Mg I, and Na I isoelectronic sequences.

The spectrum of Mg III has been thoroughly investigated in the wavelength range 720 to 6 600 Å by using powerful spectrographs. The earlier analysis has been checked and slightly revised. The analysis has been greatly extended to configurations with higher n and l values and the following configurations are now complete: 2p⁵3s, 4s, 5s, 3p, 4p, 3d, 4d, 4f, 5f, and 5g. Accurate level values have been derived. The number of identified lines is 373. The ionization energies have been derived by applying the polarization formula to 4f, 5f and 5g giving for 2p⁵²P_1½ 646 402±5 cm^-1. The 2p⁵3s, 3p, and 3d configurations are best described in the LS coupling scheme, and 4s, 5s, 4p, 4f, 5f, and 5g in the J K scheme.

The wavelengths have been measured for 200 lines of N I in the long-wave region and 71 lines in the vacuum-ultraviolet region. The latter have also been calculated from the recalculated system of energy levels. The designations 6s²P_3/2, 4d⁴D_5/2, ⁴P_{5/2, 3/2, 1/2}, ²F_5/2, and 5d⁴D_5/2, ⁴P_{5/2, 1/2} have replaced the previous designations 6s²P_1/2, 4d⁴P_5/2, ²F_5/2, ⁴P_{1/2, 3/2}, ⁴D_5/2, and 5d⁴P_5/2, ⁴D_5/2, ⁴P_3/2, respectively. The new levels 6s²P_1/2, 4p²D_{5/2, 3/2}, ²P_{3/2, 1/2}, 5p⁴D_{7/2, 5/2, 3/2, 1/2}, ⁴P_{5/2, 3/2, 1/2}, ⁴S_3/2, ²P_{3/2, 1/2}, ²S_1/2, 4d⁴D_{7/2, 3/2, 1/2}, 5d⁴F_3/2, ⁴D_{7/2, 3/2, 1/2}, ⁴P_3/2, and 6d⁴F_{9/2, 7/2} have been established. The limit 2s²2p²³P₂ has been determined to 117 356.46±0.12 cm^-1.

The 3 250 Å bands of SiH and SiD first reported by Verma have been observed in absorption in a flash discharge through SiH₄ and SiD₄ respectively. High resolution spectrograms have been measured and the rotational analysis confirms that the transition is of the type ²Σ^+_2Π. Perturbations from another ²Σ⁺ state are observed and partly analyzed. A predissociation that appears to be of different character than in the similar CH molecule is discussed. Some derived molecular constants are given below (in cm^-1).

By using statistical methods improved spectroscopic constants are obtained for the A²Σ⁺ and X²Π_i states of OH. In particular careful attention has been paid to the Λ-doubling constants. The difficulty of choosing a formula to express all the energy levels is discussed and complete tables of term values are included. The term values are judged to be accurate to better than 0.1 cm^-1.

This paper outlines a theory, which is to be used for a numerical investigation of the non-linear interaction of three electrostatic plasma waves.

⟨110⟩ "spots" deposited on a cylindrical collector by the sputtering of a {100} radioactive single crystal of gold have been analyzed and shown, for certain orientations, to have an internal structure.

The ESCA spectra of C₆H₆, C₄H₄S, C₄H₅N and C₄H₄O have been studied using MgKα radiation, 1253.6 eV. The study included both the core orbitals and the valence orbitals. The C1s chemical shifts have been compared with the shifts predicted by the potential model, using both CNDO and ab initio gross atomic charges. We have obtained the binding energies of the deeper lying valence orbitals which cannot be reached by ultraviolet radiation. Further, the valence orbital spectra have been analysed using line intensities predicted from the atomic population of the molecular orbitals.