Topic

# Spectral line

About: Spectral line is a research topic. Over the lifetime, 32353 publications have been published within this topic receiving 808005 citations.

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01 Jan 1935

TL;DR: In this paper, the quantum mechanical method is applied to the theory of complex spectra and the Russell-Saunders case is used to obtain the energy levels of one-electron spectra.

Abstract: 1. Introduction 2. The quantum mechanical method 3. Angular momentum 4. The theory of radiation 5. One-electron spectra 6. The central-field approximation 7. The Russell-Saunders case: energy levels 8. The Russell-Saunders case: eigenfunctions 9. The Russell-Saunders case: line strengths 10. Coupling 11. Intermediate coupling 12. Transformations in the theory of complex spectra 13. Configurations containing almost closed shells. X-rays 14. Central fields 15. Configuration interaction 16. The Zeeman effect 17. The Stark effect 18. The nucleus in atomic spectra Appendix. Universal constants and natural atomic units.

2,607 citations

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01 Jan 1935

TL;DR: In this paper, the quantum mechanical method is applied to the theory of complex spectra and the Russell-Saunders case is used to obtain the energy levels of one-electron spectra.

Abstract: 1. Introduction 2. The quantum mechanical method 3. Angular momentum 4. The theory of radiation 5. One-electron spectra 6. The central-field approximation 7. The Russell-Saunders case: energy levels 8. The Russell-Saunders case: eigenfunctions 9. The Russell-Saunders case: line strengths 10. Coupling 11. Intermediate coupling 12. Transformations in the theory of complex spectra 13. Configurations containing almost closed shells. X-rays 14. Central fields 15. Configuration interaction 16. The Zeeman effect 17. The Stark effect 18. The nucleus in atomic spectra Appendix. Universal constants and natural atomic units.

2,552 citations

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01 Jan 1974TL;DR: SpectSpectral Line Broadening by Plasmas as discussed by the authors provides a theoretical overview of the spectral line broadening mechanism and its application in the field of plasma spectroscopy, with a focus on spectral lines.

Abstract: The usefulness of line-profile measurements as a diagnostic tool in plasma physics depends on our ability to analyze and interpret the data. In his earlier book, "Plasma Spectroscopy", * Hans Griem developed the theory of the various broadening mechanisms. His new book, "Spectral Line Broadening by Plasmas", closes the gap between theory and practical application for people who are not already expert in the theory of spectral lines.

2,509 citations

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TL;DR: The Astrophysical Plasma Emission Code (APEC) as mentioned in this paper uses atomic data from the companion ASTPED database to calculate spectral models for hot plasmas, such as collisional and radiative rates, recombination cross sections, dielectronic recombination rates, and satellite line wavelengths.

Abstract: New X-ray observatories (Chandra and XMM-Newton) are providing a wealth of high-resolution X-ray spectra in which hydrogen- and helium-like ions are usually strong features. We present results from a new collisional-radiative plasma code, the Astrophysical Plasma Emission Code (APEC), which uses atomic data in the companion Astrophysical Plasma Emission Database (APED) to calculate spectral models for hot plasmas. APED contains the requisite atomic data such as collisional and radiative rates, recombination cross sections, dielectronic recombination rates, and satellite line wavelengths. We compare the APEC results to other plasma codes for hydrogen- and helium-like diagnostics and test the sensitivity of our results to the number of levels included in the models. We find that dielectronic recombination with hydrogen-like ions into high (n = 6-10) principal quantum numbers affects some helium-like line ratios from low-lying (n = 2) transitions.

2,124 citations

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TL;DR: A computer-accessible catalog of submillimeter, millimeter, and microwave spectral lines in the frequency range between 0 and 10 000 GHz (i.e. wavelengths longer than 30 μm) that has been constructed by using theoretical least-squares fits of published spectral lines to accepted molecular models.

Abstract: This paper describes a computer-accessible catalog of submillimeter, millimeter, and microwave spectral lines in the frequency range between 0 and 10 000 GHz (i.e. wavelengths longer than 30 μm). The catalog can be used as a planning guide or as an aid in the identification and analysis of observed spectral lines in the interstellar medium, the Earth’s atmosphere, and the atmospheres of other planets. The information listed for each spectral line includes the frequency and its estimated error, the intensity, the lower state energy, and the quantum number assignment. The catalog is continuously updated and at present has information on 331 atomic and molecular species and includes a total of 1 845 866 lines. The catalog has been constructed by using theoretical least-squares fits of published spectral lines to accepted molecular models. The associated predictions and their estimated errors are based upon the resultant fitted parameters and their covariance. Future versions of this catalog will add more atoms and molecules and update the present listings as new data appear. The catalog is available on-line via anonymous FTP at spec.jpl.nasa.gov and on the world wide web at http: //spec.jpl.nasa.gov.

2,098 citations