Deuterium arc lamp

However, lamps using deuterium have a longer life span and an emissivity (intensity) at the far end of their UV range which is three to five times that of an ordinary hydrogen arc bulb, at the same temperature.

A deuterium lamp uses a tungsten filament and anode placed on opposite sides of a nickel box structure designed to produce the best output spectrum.

This causes a larger population of molecules and a greater emissivity (light output) of UV in the molecular part of the spectrum that is farthest into the ultraviolet.

Instead, a fused quartz, UV glass, or magnesium fluoride envelope is used depending on the specific function of the lamp.

The deuterium lamp's continuous spectrum is useful as both a reference in UV radiometric work and to generate a signal in various photometric devices.

Touching the bulb directly even when cool could deposit impurities onto the casing that strongly absorb the short wavelength UV and therefore reduce output intensity.

Deuterium arc lamp
Emission spectrum of an ultraviolet deuterium arc lamp showing characteristic hydrogen Balmer lines (sharp peaks at 486 nm and 656 nm labeled D β and D α from left to right respectively), continuum emission in the ~160-400 nm region and Fulcher band emission between around 560 to 640 nm. The emission spectrum of deuterium differs slightly from that of protium (hydrogen-1) 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. Deuterium is used rather than normal hydrogen because of its greater intensity of UV emission in the molecular band.