Weak Atomic Lines Research Articles

Zeeman effect of weak La I lines investigated by the use of optogalvanic spectroscopy

New Landé- gJ factors of 35 energy levels of La I, found from investigations of 40 spectral lines in the wavelength range 562.959÷609.537nm, were determined. As a source of free La atoms a hollow cathode discharge lamp was used. We monitored the signal of the optogalvanic effect appearing when a laser beam is passing through the hollow cathode. Spectra were recorded in the presence of a magnetic field of about 800G produced by a permanent magnet, for two linear polarizations of the exciting laser light. Optogalvanic spectroscopy is a very sensitive method, so we were able to observe the Zeeman effect of very weak atomic lines. In this way we have determined for the first time the Landé-gJ factors for 35 recently found levels of neutral La. The Landé gJ- factors for several other levels were reinvestigated.

Spectral signature of native CN bonds for bacterium detection and identification using femtosecond laser-induced breakdown spectroscopy

A sample of Escherichia coli has been analyzed by laser-induced breakdown spectroscopy (LIBS) using femtosecond pulses. The spectrum shows strong CN molecular bands due to the direct ablation of native CN molecular bonds from the bacteria in contrast with weak atomic lines from carbon. The native nature of the observed CN bonds is supported by the kinetic behavior of the CN band head which rapidly decays with a time constant of 94 ns, while for a pure graphite sample the CN band head increases with a delay of 450 ns due to recombination with the ambient air. Moreover, about hundred resolved lines belonging to 12 atomic or molecular species are recorded, providing a valuable spectral signature to identify the bacterium.

Relative abundances in metal-poor stars. II - The carbon-to-iron ratio

view Abstract Citations (41) References (50) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Relative abundances in metal-poor stars. II. The carbon-to-iron ratio. Peterson, R. C. ; Sneden, C. Abstract The abundance of carbon has been determined (or an upper limit established) by spectral synthesis of CH features in a dozen field dwarfs and subgiants of metallicities 1/5 to 1/100 solar. All program stars were selected from the Eggen high-velocity catalog, observed with the SAO echelle-Kron system at Mount Hopkins, Arizona, and analyzed by using model-atmosphere computations of broad-band colors and weak atomic lines. The CH features reveal that all these stars have essentially the solar carbon-to-iron ratio, given the plus or minus 0.2 dex uncertainty in the normalization to the solar value, and the plus or minus 0.14 dex uncertainty in an individual stellar carbon-abundance determination relative to others. Several implications of this uniformity for studies of the evolution of the Galaxy as a whole are briefly discussed. Publication: The Astrophysical Journal Pub Date: November 1978 DOI: 10.1086/156557 Bibcode: 1978ApJ...225..913P Keywords: Abundance; Carbon; Dwarf Stars; Iron; Stellar Atmospheres; Stellar Models; Galactic Evolution; Hydrogen Atoms; Metals; Spectrum Analysis; Astrophysics; Carbon:Metal-Poor Stars full text sources ADS | data products SIMBAD (13) Related Materials (2) Part 1: 1978ApJ...222..595P Part 3: 1981ApJ...244..989P