![]() The optogalvanic effect in both HCLs is produced by a laser diode radiated at the wavelength that corresponds to neon transition 1s2-2p2 at 659.89 nm. ![]() This paper presents a study of two commercial hollow-cathode lamps (HCLs) with the intention of demonstrating different phenomena in gas discharges. Optogalvanic effect and laser-induced current oscillations in hollow-cathode lampsĮldakli, Mohsan S. With these spectra we are measuring and calibrating the positions of these molecular lines in order to make them suitable for spectrograph calibration.In the near infrared region, U/Ne hollow cathode lamps give a higher density of calibration lines than Th/Ar lamps and will be implemented on the upgraded CRIRES+ spectrograph on ESO’s Very Large This significantly exceeds the resolving power of most astronomical spectrographs and resolves many of the molecular lines of ThO. Second, we have measured the spectrum of a recent, contaminated Th/Ar hollow cathode lamp using a high-resolution Echelle spectrograph (Madison Wisconsin) at a resolving power (R~ 250,000). Interactive zooming and the ability to convolve any of the spectra with a Gaussian or uploaded instrument profile enable the user to see immediately what the spectrum would look like at the particular resolution of their spectrograph. Spectra of hollow cathode lamps at up to 3 different currents can now be displayed simultaneously. First, we have expanded and improved the NIST Standard Reference Database 161, "Spectrum of Th-Ar Hollow Cathode Lamps" to cover the region 272 nm to 5500 nm. In addition, recent changes in regulations regarding the handling of thorium have led to a degradation in the quality of Th/Ar calibration lamps, with contamination by molecular ThO lines that are strong enough to obscure the calibration lines of interest.We are pursuing two approaches to these problems. However, the high density of the spectrum that makes it attractive for calibrating high-resolution spectrographs is a detriment for lower resolution spectrographs and this is not obvious by examination of existing linelists. Thorium is an attractive element for calibration as it has a single isotope, has narrow spectral lines, and has a dense spectrum covering the whole of the visible region. Low-current Th/Ar hollow cathode lamps have long been used for calibration of astronomical spectrographs on ground-based telescopes. Nave, Gillian Shlosberg, Ariel Kerber, Florian Den Hartog, Elizabeth Neureiter, Bianca Spectra of Th/Ar and U/Ne hollow cathode lamps for spectrograph calibration ![]() The role of the narrowness of the exciting lines in increasing the signal-to-scattering ratios is stressed. The performances of the hollow-cathode lamp and those of the customary metal vapour discharge lamps for thallium, indium and gallium are compared. Sensitivities ranging from 0.03 to 2 mug ml were obtained for 12 elements. The discharge current ranged from 300 to 500 mA, and the flowing argon pressure between 0.4 and 4 mbar. The observations were made in collaboration with the European Southern Observatory (ESO), in order to provide calibration reference data for new high-resolution Echelle spectrographs, such as the Cryogenic High-Resolution IR Echelle Spectrograph (), ESO's new IR spectrograph at the Very Large Telescope in Chile.Īpplication of a demountable water-cooled hollow-cathode lamp to atomic-fluorescence spectrometry.Ī demountable water-cooled hollow-cathode lamp has been investigated as a primary source in atomic fluorescence spectrometry. These observations establish more than 2400 lines that are suitable for use as wavelength standards in the range 691 nm to 5804 nm. SRD 161 NIST Spectrum of Th-Ar Hollow Cathode Lamps (Web, free access)  This atlas presents observations of the infra-red (IR) spectrum of a low current Th-Ar hollow cathode lamp with the 2-m Fourier transform spectrometer (FTS) at NIST. National Institute of Standards and Technology Data Gateway
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