Edward Paul

Interferometric Wavelength Determinations in the First Spectrum of 136 Xe

Interferometric wavelength determinations in the first spectrum of 131Xe, covering the photographically observable region between 3949 and 11 088 A, and the nonphotographic region between 12 626 and 35 079 A, are reported. Photographic intercomparisons were made with I.A.U.-recommended standards of 198Hg at 4047 and 4359 A. Study of the properties of several ir lines of Ar i led to the adoption of the line of wavelength (in air), 16 940 A, as the most suitable standard for the radiometric intercomparisons. Wavelengths of a total of 221 lines are reported, including 15 between 12 626 and 35 070 A. Energy levels have been determined to the extent permitted by the interferometric observations. All material on this spectrum presented at recent meetings of the Optical Society of America, or contained in internal reports, is included.

First Spectrum of Chlorine; an Extension Based on Observations in the 7000 to 25 000 A Region*†

The spectrum of neutral chlorine excited by means of a Raytheon Microtherm unit in electrodeless tubes filled with the pure gas has been observed in the region between 10 000 and 25 000 A. A description has been prepared giving wavelengths, wave numbers, and relative intensities of 283 radiometrically observed lines. Newly classified lines selected from a recent set of photographic observations by Corliss in the interval between 7000 and 10 000 A are included. Extensions to the established classification include identification of all 22 of the previously unobserved levels of the family associated with the 3P ion limit, comprising the levels from the 3s23p45s and 3s23p43d configuration. From a study of this material, along with his list of wave numbers, Corliss has found fourteen new odd levels. Further systematic combing of the data by use of an automatic computing program has revealed four additional odd levels. The new odd levels originate probably in the 3s23p44f configuration.

First Spectra of Chlorine, Bromine, and Iodine in the 1.8–4.0-μm Region

Use of liquid-nitrogen-cooled lead sulfide detectors has permitted the extension of observations of the first spectra of the halogens in the infrared region as far as 4.0 μm. Descriptions, comprising wavelengths, wave numbers, intensities, and classifications, are presented that serve to close the gap between the upper wavelength limit of the detailed published analyses of these spectra at about 2.5 μm and the groups of recently classified lines near 4 μm, and also to report newly observed lines in the 1.8–2.5-μm region made accessible by detectors of improved response characteristics. Listed wavelengths of observed and identified lines are calculated from established values of the energy levels. The descriptions should facilitate the identification of halogen lines in mixed spectra excited in electrodeless tubes containing halogen compounds.

Spectra of the Noble Gases in the 4-μ Region*

The spectra of neon, argon, krypton, and xenon have been observed in the wavelength region 3.8 to 4.1 μ, using an infrared spectrometer equipped with cooled lead sulfide detector. The most important observations are of the near-hydrogenic and closely pair-coupled 4f–5g transitions, which establish for the first time all the 5g level pairs lying below the first ionization limit of each element. A detailed investigation of the theoretically predicted 4f–5g energy levels and relative line strengths shows very good agreement with observation. Various p–s, p–d, and d–f transitions have been identified, the most significant new result being the establishment of the level pairs 5f[412]4,5 and 5f[312]3,4 of Ne i, which previously had been only estimated.

Interferometric Observations in the Spectra of 86 Kr

Wavelengths in the first and second spectra of 86Kr are reported. Included are results of observations in the nonphotographic infrared region and conventional intercomparisons by use of Fabry-Perot interferometers in a vacuum, with the primary wavelength standard at 6057 A, originating in a microwave-excited electrodeless discharge operated at the triple point of nitrogen. The wavelengths are in the region between 3623 and 28 663 A. All wavelengths of these spectra that have been reported at recent meetings of the Optical Society of America or in internal reports are included.

The Observation of Extraphotographic Infrared Atomic Emission Spectra

The extension of observation of atomic line emission spectra into the extraphotographic infrared region by high-resolution methods has been accomplished by procedures now well established but which have not found widespread application. Owing to the nonintegrating character of radiometric detecting devices, the observations are always energy-limited. This handicap may be overcome by a threefold approach: utilization of a fast optical system; optimizing the detecting and amplifying system; and developing sources of maximum energy output consistent with the character of the spectrum to be studied. Successful systems for use with a high-resolution grating spectrometer are described. Examples are given of the extension of the observation of several spectra to a fairly easily attainable limit of 4 μ by use of lead sulfide detectors designed for liquid nitrogen cooling.

Newly Observed Lines of Argon i and Krypton i in the Lead-Sulfide Region

Recordings of the spectra of argon and krypton from microwave-excited electrodeless sources have led to observation of a considerable number of previously unreported lines. These new observations comprise 30 lines of argon between 14 000 and 25 000 A, and 10 lines of krypton between 20 000 and 25 000 A. All are accounted for as transitions between known energy levels.