Sunlight, continuous spectrum

To understand the significance of the hydrogen emission spectrum, we must first describe the continuous spectrum that resuits when white iight is passed through a prism, as shown in Fig. 7.7(a). This spectrum, iike the rainbow produced when sunlight is... 

A 6000W xenon arc Atlas Weather-Ometer (] ) equipped with Corning No. 77 +0 horosilicate inner and outer filters was used as a laboratory light source because its emission spectrum is similar to that of sunlight, as illustrated in Fig. 1. The Weather-Ometer was operated with the lamp on continuously and the exposure chamber was maintained at a black panel temperature of ll+5 5°F and a relative humidity of 30 5. ... 

The arc lamp with the best resemblance to sunlight is the xenon arc lamp, although the development of new metal-halide lamps has led to competition for that claim. The spectral outputs of these two types are shown in Figure 3.2 and Figure 3.3. The xenon arc has a relatively smooth continuous output spectrum with some line emissions superimposed in the region of 450 to 500 nm, whereas the metal-halide lamp is more uniform across the 350 to 550 nm region. 

As an alternative to accelerated outdoor methods, laboratory equipment can be used which aims to reproduce, within a cabinet, the spectrum or part of the spectrum of natural sunlight combined with heating and/or moisture and/or darkness cycles. Test panels are exposed in such equipment which can then be run continuously. 

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