Sharp series

Abstract: Extreme ultra-violet spectra, to 136 A, of twenty light elements, H to Cu.—Using the vacuum apparatus and explosive spark previously described, many plates have been made with a great variety of electrodes. By measuring and comparing thirty of these, over 800 lines between 136 A and 1862 A have been identified as belonging to one or other of the twenty elements studied. For H(1) only two lines, members of the Lyman series, were found; for He(2), and Li(3) none, though carefully looked for; for Be(4) one doubtful weak line; for Na(11) one strong line λ372.3 and one doubtful one λ376.6; for the other elements B(5), C(6), N(7), O(8), F(9), Mg(12), Al(13), Si(14), P(15), S(16), Cl(17), K(19), Ca(20), Cr(24) and Cu(29) from 9 to 160 lines each, all given in Tables. The strongest lines for each of the light elements are L series lines and form a progression like Moseley's for x-ray lines: Li (red), Be 3131.19, B 2066.2, C 1335.0, N 1085.2, O 834.0, F 656.4, Na 372.3, Mg 231.6, Al 162.4. These are mainly doublets, the separation increasing regularly with atomic number. M spectra also extend to shorter wave-lengths the higher the atomic number, reaching about 155 A for Cu, but on account of the complexity of the spectra only a few lines have been identified. Other series lines identified are: 2 diffuse series lines and 2 sharp series lines due to Mg+ or Mg(II), 5 lines due to Al+ and 9 due to Al++ or Al(III), 11 lines due to Si(IV) and probably the first terms of the principal series and of the diffuse series of P(V). Interpretation in terms of Bohr theory. By use of the Kossel equation in connection with available data it is shown that for Na, 372.3 A corresponds to an electron jump from the M shell to L(I); for Mg, 320.9, and 323.2 and 231.6 correspond to M(I)→L(II), M(I)→L(III) and M(III)→L(I); for Al, 162.4, 200.0, 230.8, 186.9 may correspond to jumps from shell 3 to the L shell; for Ca, 655.9 and 669.6 correspond to jumps N(I)→M(II) and N(I)→M(III). These interpretations give values of constants of the L and M levels of the atoms as follows: For Na, L(I), ν/R=2.826; for Mg, L(I) 4.298, L(II) 3.402, L(III) 3.381; for Al, L(I) 6.045, L(II) L(III) 5.008. The square roots of these values are linear functions of the atomic number. For Ca M(II), ν/R=1. 839, M(III) 1.810. From the difference L(II)—L(III) for Mg, the screening constant comes out 3.1; from the difference M(III)—M(II) for Ca, the constant is 7. These results are all in good agreement with other data. Ionization produced by explosive spark in vacuum.—The strongest spectrum lines are generally emitted by stripped atoms, that is atoms with no valence electrons left, Na(I), Mg(II), Al(III), Si(IV), P(V), etc.

Abstract: The oscillator strengths for the sharp, principal, and diffuse series in the spectra of Al I, Ga I, In I, and Tl I are calculated as well as the lifetimes of their lowest excited states. The wave functions that were used were calculated by employing a relativistic semiempirical method which included exchange effects. Very good agreement with the most reliable experimental data was obtained for the fik values in the sharp series as well as for the calculated lifetimes. The discrepancies in the diffuse series are ascribed to the failure of the one-electron approach in the case of strongly perturbed series. The observed deviations in the relative line strengths from the values predicted neglecting the spin–orbit interaction were also investigated. Some systematic trends in the calculated oscillator strengths that were found for the sharp and principal series appear to be corroborated by experimental data for the sharp series in the spectra of Al I, Ga 1, In I.andTl 1.

Abstract: This paper is mainly a report of further observations on the Stark-effect in helium made with a view to establishing various definite Stark patterns for the series lines. It thus appears as an extension to an earlier paper in which it was pointed out that a plan for Stark patterns is contained implicitly in the Bohr perturbation theory of the Stark-effect as developed by Kramers to predict connections between the hydrogen fine structure and the components observed in high fields. This plan, which on the perturbation theory might be expected to make its appearance in helium, receives somewhat detailed support from the present data, and will be outlined in later paragraphs. It should be stated now, however, that while the detailed analyses here given may be regarded as an extension to the observations by Stark and Nyquist, they offer definite reasons for a rather extensive revision of the complex analyses reported by Takamine and Kokubu. Soon after his discovery of this effect Stark suggested that it might be found to be of the same nature for the various members of a single spectral series. He noted, in particular, that on the early plates certain principal and sharp series lines of helium were merely displaced without being split by the applied electric field. In the following paper Stark and Kirschbaum gave the results of a more complete examination of the Stark-effect for the series lines of orthohelium, parhelium, lithium, and the doublets of calcium. With the single exception of the parhelium line λ 3614, which appeared to be double, they found all principal and sharp series lines simply displaced. The two components of each calcium doublet were shifted in the same direction, and by nearly the same amounts.

Abstract: Emission spectra of Rb‐rare gas mixtures (Rb–He, Rb–Ne, Rb–A, Rb–Kr, and Rb–Xe) were investigated in search of diffuse bands recently observed in the absorption spectra of Cs and Rb in the presence of foreign gases. In addition to the bands accompanying principal series lines observed in absorption, a number of new bands (interaction satellites) were found on the long wavelength side of the Rb lines belonging to the sharp and the diffuse series. The bands accompanying sharp series lines are very narrow and intense and have the appearance of somewhat broadened spectral lines. The bands at diffuse series lines are less intense but much wider, and are separated from the atomic lines considerably more than the bands at the sharp series lines. The bands on the short wavelength side of the atomic lines were found only at the principal series lines. Extensive continua were observed on the long wavelength side of the resonance lines and the second doublet of the principal series. At the resonance lines these continua show fluctuations of intensity differing for the various mixtures and cover distances of several hundred wave numbers. The red bands, the violet bands, and the continua may appear simultaneously and do not require different operating conditions for their observation.