Mercury-xenon lamp spectral output

Elg. 7,13. Spectral output of high-pressure mercury/xenon lamp. 

For operation over a limited spectral region primarily confined to the UV (200 - 350 nm), high wattage deuterium lamps are available and have been used in select applications. The emission region for these lamps is well defined, frequently encompassing approximately 1 mm. However, D2 lamps provide an output that is severely limited above 350 nm, and for operation at longer wavelengths a second source is necessary. For this reason, most conventional applications utilize a Xe or mercury-xenon arc lamp as the source of choice for CD measurements. 

Mercury-Xenon (Hg-Xe) Arc Lamps. One can also use high-pressure Hg-Xe lamps. These have higher intensities in the UV than Xe lamps, and the presence of Xe tends to broaden the spectral output. The output of these lamps is dominated by the Hg lines and is similar to that shown for the Hg lamps in Figure 2.3, but there is slightly more output between the Hg lines. When first started, the Hg-Xe lamp output is due mostly to Xe. As the lamp reaches operating temperature, all the Hg becomes vaporized, and the Hg output becomes dominant. 

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