High-current hollow-cathode source as a radiant intensity standard in the 40-125-nm wavelength range.
The radiant intensity of VUV emission lines of a high-current hollow-cathode source has been determined for the 40-125-nm spectral range. The source is operated at a constant current of 1 A with an aluminum cathode. Different rare gases are alternatively used as the buffer gas at pressures of ~100 Pa. The radiant intensity has been determined by comparison with the calculable spectral radiant flux of the electron storage ring BESSY. Radiant intensities of the emission lines are in the 7-1400-µW/sr range. The long-term reproducibility of the radiant intensity of the source is within ±10% (2σ value). The systematic uncertainty of the radiometric calibration is better than 9% (√32σ value).
Continuous calibration of a vacuum ultraviolet system from 65 to 125 nm by a cascade arc and comparison with the calibrated line radiation of a hollow cathode.
A high-power stationary helium cascade arc has been developed as a standard source for continuum radiation in the VUV spectral range from 65 to 125 nm. The calibration of the VUV system response was based on the calculated and measured continuum radiation of a 2-mmphi pure He arc. Diagnostics of the arc plasma in partial thermal equilibrium yielded the electron density and the temperature that were inserted in the calculations of the continuous radiation. The results were compared with the helium, argon, and krypton radiation lines of a high-current hollow cathode lamp. This lamp was built according to the construction drawings of a hollow cathode, which was calibrated by means of the electron synchrotron radiation at the Physikalisch Technische Bundesanstalt Berlin.
Atomic absorption spectroscopy in the 100-600 a wavelength range.
Previous obstacles to observation of line absorption spectra in the vacuum uv below 600 A have been overcome by: (a) development of a containment device for metal vapors in a windowless system and with a negligible pressure of background gas; (b) use of a compact source of background continuum; and (c) exploitation of a normal incidence grating spectrograph which can be used with (b) to a wavelength below 300 A. As examples, the inner shell absorption spectra of Ar, Kr, Xe, Na, K, and Rb are reproduced. Slight modification of the techniques under (a) and (c) can be used when an electron synchrotron background continuum is substituted for (b).