William F. Meggers

Wave-Lengths of Mercury 198

The wave-lengths of 26 visible and ultraviolet radiations from H80198g have been measured to eight figures relative to 5460.7532A, provisionally adopted for the green line. A water-cooled electrodeless lamp containing two milligrams of artificial H80198g served as a light source when excited with radio waves of 100 Mc frequency. This lamp illuminated a Fabry-Perot interferometer and a large quartz spectrograph with which the interference patterns were photographed. Measurements of these patterns yielded relative wave-lengths with probable errors usually less than 0.0001A. In addition to demonstrating that H80198g 5460.7532A provides a practically perfect primary standard of length, this paper presents preliminary values of 27 superior spectroscopic standards which show that differences among vacuum wave numbers recur within the accuracy of the measurements, and that all the existing dispersion curves for air are incorrect.

The spectrochemistry of technetium and promethium

Abstract For spectrochemical detection or determination of technetium ( 43 Tc) the wavelengths and relative intensities of 407 lines are presented. The wavelengths range from 8829·80 to 2298·10 A, and the intensities from 1000 to 10. Excitation energies of 133 of these Tc lines are known. For spectrochemical detection of promethium ( 61 Pm) the wavelengths and relative intensities of 272 lines are given. The wavelengths range from 6811·28 to 2632·00 A, and the intensities from 100 to 10.

The Centennial of Spectrochemistry—Presented at the Washington Meeting of the Optical Society of America, April 7, 1960

The birth and growth of spectrochemistry are reviewed on the occasion of its centennial. The origin of spectrochemistry is found in the two classical memoirs published by Robert Bunsen and Gustav Kirchhoff a century ago in Poggendorff’s Annalen, in which they gave the first definite and general answer to the question as to whether the bright lines in the spectrum of a glowing gas are dependent exclusively on its chemical composition. We find there also the foundations of astrophysics and a report on the first discovery of a new chemical element by spectral analysis (cesium).Short biographical sketches of Bunsen and Kirchhoff are given, and the major conclusions of their two famous memoirs are cited. The growth of this new method of chemical analysis is then briefly traced to this centennial year, when such analyses are already being widely made in science and technology by electronic automation.

Fundamental Research in Atomic Spectra

The discovery, refinement, and quantum interpretation of atomic energy levels has been the principal goal of fundamental research in atomic spectra during the past quarter century. Analyses of the fine structure of spectra have revealed the electronic structures and the ionization potentials of atoms and ions; studies of hyperfine structure of spectral lines have yielded data on the mechanical, magnetic, and electric-quadrupole moments of atomic nuclei. This paper rates the fine structure analyses of 504 spectra of 84 chemical elements, and quotes the nuclear moments for 184 isotopic species.

RELATIVE INTENSITIES FOR THE ARC SPECTRA OF SEVENTY ELEMENTS

Abstract The relative intensities, or radiant powers, of 39,000 spectral lines with wavelengths between 2000 and 9000 A have been determined on a uniform energy scale for seventy chemical elements. This was done by mixing 0·1 at. per cent of each element in powdered copper, pressing the powder mixture to form solid electrodes which were burned in a 10-A, 220-V d.c. arc, and photographing the spectra with a stigmatic concave grating while a step-sector was rotating in front of the slit. The sectored spectrograms facilitated the estimation of intensities of all element lines relative to copper lines which were then calibrated on an energy scale provided by standardized lamps, and all estimated line intensities were finally adjusted to fit this calibration. Comparisons with other intensity measurements in individual spectra indicate that the spectralline intensities may have errors of 20 per cent, but they first of all provide uniform quantitative values for the seventy chemical elements commonly determined by spectrochemists. The complete data are being published as a National Bureau of Standards Monograph. About 1100 of the lines are presented in this paper as a list of the strong lines of each element. Energy levels and term combinations are given for each classified line.

The spectrochemistry of actinium

Abstract For spectrochemical detection or determination of actinium (89Ac) the wavelengths and estimated relative intensities (100 or greater) of 109 strong lines are presented. The wavelengths range from 2558.08 to 7866.10 A. Thirty-two lines are characteristic of Ac I, 63 belong to Ac II, 7 are assigned to Ac III, 2 possibly to Ac IV, and 5 to Ac0. The energy levels involved in the production of lines in the first three spectra of actinium are given. Within the range of these observations the strongest Ac I line is the transition 6d7s22D1 1 2 –6d7s(a3D)7p2Fo2 1 2 with wavelength 4179.98 A and intensity 1000 in the arc or hollow cathode. The strongest line of Ac II appears to be 6d7s3D3−7s(2S)7p3Po2 with wavelength 4088.44 A, and intensity 3000 in the spark. The strongest observed line has a wavelength 2626.44 A, and intensity 5000 in the spark; it represents the transition 7s2S0 1 2 −7p2Po1 1 2 in Ac III, and must be regarded as the raie ultime in high-voltage condensed electrical discharges.

Detailed Subject Index

Absorption, of atomic radiation, 2764, 3389 Abstracts, of 1945 literature, 2514 of 1940 to 1945 literature, 2776, 2805 Accuracy (see also Precision) contribution of source unit to —, 3568 effect of microstructure of electrodes on —, 2988 effect of photographic plate on —, 2784 factors affecting —, 2950 improvements in —, 3377, 3378 in flame photometry, 2977 in photographic photometry, 2920 of plate calibration, 3014, 3016 of steel anal., 2780, 2851, 3341 statistical fluctuations in anal., 2893 Air, detection of Pb in — by Geiger counter, 3200 detn. of Be in dust from —, 3513 detn. of Pb in —, 3079, 3451 Albite, anal, of —, 2998 Alkali salts, detn. of Li in —, 2420b Alkaline earths, detn. of Li in —, 2420b Alum, detn. of Ca in —, 3537 detn. of Mg hi —, 3183 Alumina (see also Bauxite) anal, of —, 3550 Aluminum, anal, of — at University of Ghent, 2672 anal, of — by solns., 221 la detn. of Al, Cu, Fe, Mg hi —, 2651 detn. of Be hi — by soln. method, 3495 detn. of Cd, Ni, Pb, Sn hi recast —, 3019 detn. of Cu, Fe, Mg, Mn, Si hi — with unproved excitation source, 2626 detn. of Cu, Fe, Si, Zn hi —, 2876, 3469 detn. of Fe, Mg, Si hi —, 2549 detn. of Fe, Si hi —, 2674, 2894 detn. of Ga hi —, 3252, 3380 detn. of Mg hi — by line-width method, 2491 detn. of Mn hi — by line-width method, 1990a,1990b detn. of Mn, Ni hi —, 2817 detn. of Na hi —, 2556, 2975 detn. of Na hi — by flame photometer, 3340 detn. of Si hi —, 2554 detn. of Zn hi —, 2877, 3373 effect of circuit hi anal, of —, 2170b effect of sample treatment hi detn. of Si hi—,2554 Aluminum alloys (see also Duralumin, Silumin) anal, by photoelectric spectrometer, 2621, 3357 anal, of — with intermittent a-c arc, 3224 calibration of standard samples of —, 3221 conditions for anal, of —, 2l70c control of — by photoelectric method, 2867 detn. of Al, Fe, Mg, Mn, Si, Zn hi —, 3334 detn. of Be hi —, 3161 detn. of Cr, Cu, Fe, Mg, Mn, Ni, Pb, Si, Sn, Ti, Zn hi —, 2824 detn. of Cr, Cu, Fe, Mg, Mn, Ti, Zn hi —, 3238 detn. of Cu hi —, 2534, 2809 detn. of Cu, Fe, Mg, Mn hi —, 2826 detn. of Cu, Fe, Mg, Mn, Si hi —, 3230 detn. of Cu, Fe, Mg, Mn, Si, Ti, Zn hi —, 2216b, 2569 detn. of Fe, Mg, Mn, Si hi — with phototubes, 2895 detn. of Mg hi —, 3572 detn. of Mg hi — by self-reversal, 2769 detn. of Mg, Zn hi —, 3042 effect of alloying components on spectra of—,3308 effect of background on detn. of Cu hi —, 3523 effect of heat treatment hi anal, of —, 2570, 3314a effect of heat treatment of electrodes on intensities, 3005 effect of microstructure on anal, of —, 2763 effect of pre-spark on anal, of —, 2570 effect of Si content in anal, of Al-Si —, 3536 effect of microstructure on anal, of —, 2763 prepn. of standard samples for —, 2732 sampling of —, 2733 semiquant. anal, of — scrap, 2731 study of diffusion hi —, 2919 visual anal, of —, 3047 visual sorting of —, 2791, 2797 Aluminum and alloys, anal, of —, 3110 British Aluminum Co. methods for anal. of—,2102a detn. of Cr, Cu, Fe, Mg, Mn, Ni, Pb, Si, Sn, Ti, Zn hi —, 2813 detn. of Mg, Si hi — by two-line method, 2962 review of anal, of —, 2756a

Wavelengths of Mercury 198

The international standard of length, a platinum‐iridium bar located in a vault at the International Bureau of Weights and Measures near Paris, was measured relative to the wavelength of the red cadmium line by Michelson in 1892, and the value he derived for the wavelength of the red cadmium radiation has been provisionally adopted as the international standard of length.

Principals and Principles of Spectrochemical Analysis

The history of science abounds with examples of men who observe natural phenomena but are unable to explain or apply them until a