L4-B

Xenon Arc Lamps
Xenon arc lamps have a spectrum that is relatively broad and featureless throughout the visible and ultraviolet regions, in contrast to the strong line structure of the krypton arc lamp. Their spectral distribution closely matches the solar spectrum in these regions, so that they often are used as the light source for solar simulators. These arc lamps do have line structure in the infrared spectrum, but they are not so well-matched to the Nd:YAG absorption as the krypton lamp. They have been used to pump alexandrite lasers, however.
The relatively smooth spectral distribution also makes them useful for measurements of absorption and fluorescence. For these applications, the source wavelength is scanned with a wavelength-selecting element.
Mercury Arc Lamps
Mercury arc lamps feature a strong ultraviolet output with discrete lines. A spectrum for a typical mercury arc lamp is shown in Figure 7. It is apparent that the spectrum is dominated by strong discrete mercury lines through the ultraviolet and visible range. The emission spectrum extends into the deep ultraviolet, to wavelengths shorter than 300 nm.