UV spectrum

In contrast to most other UV sources, the MPL has a polychromatic spectral distribution ranging from 190 nm up to the IR. A typical spectral distribution for non-doped lamps is shown in Fig. 1. The far infra-red radiation is principally determined by the bulb temperature which ranges from 600 °C to  max. 900 °C. All other wavelength ranges directly depend on the plasma properties such as temperature, pressure, and atomic and molecular content.
The UV radiant properties of standard mercury lamps are directly linked to the radiating characteristics of atomic mercury.
The typical UV efficacy is shown in the table.

The values shown in Fig. 2 vary strongly on operating and filling conditions and are seen as typical orders. The radiant power of non-doped standard mercury MPL is dominated by its strong UVC emission which is mostly required in all germicidal applications.
By adding dopants such as iron, gallium or indium the spectral radiant power can be significantly varied. The emission can be tuned to the specific action spectra required for each application. Typical spectra are shown on the following pages. The UVC, and especially the wavelength range below 230 nm, can be enhanced by tuning the quartz and plasma properties.