Talk:Deuterium arc lamp
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[edit] Why deuterium?
The emission spectrum of deuterium differs slightly from that of protium due to the influence of hyperfine interactions, though these effects alter the wavelength of the lines by mere fractions of a nanometer and are too fine to be discerned by the spectrometer used here.
- In that case, why use deuterium at all? Why not a hydrogen arc lamp? —Keenan Pepper 03:17, 28 September 2006 (UTC)
[edit] Effective wavelength range
The spectrum and text of the current entry suggest 160 nm as the cutoff of the continuum, but one can certainly obtain a line at 121 nm Lyman-alpha (n=2->n=1) radiation. As a practical matter, the lower limit on the wavelength is probably determined by the material of the window of the lamp. —The preceding unsigned comment was added by 130.183.90.41 (talk) 14:28, 12 February 2007 (UTC).
I agree, the window is important. Another limit is the atmosphere it runs in. For instance, the spectrum shown probably cuts off at 200nm because it was run in air (oxygen is pretty much black below 200). High purity quartz will certainly get you to 180 if you nitrogen purge the instrument. A Mag fluoride window even lower, but at a cost in lifetime. Older, water cooled lamps had cemented windows, but had a short life because of diffusion through the cement. The newer lamps are air cooled and last much longer.
AJim 04:53, 22 October 2007 (UTC)
