Question

why it is necessary to use nitrogen flow before and during irradiation in a photochemical reactor

Answer 1

[about photochemical reactor]

*********The methods employed according to the present invention make it possible for the lifetime and the permissible intensity of the radiation source to be no longer limited by the luminescent materials or by their efficiency because these materials are now located outside of the gas discharge space of the lamp; and, moreover, it is considerably easier with this location to hold them at their optimum operating temperature (approximately 20° C). This fact, in turn, permits both an increase of the radiated power as well as a better and longer utilization of the luminescent materials. In the normal case, the reaction vessel and the quartz envelope are demountably connected with one another by means of matching flanges. In this way, a reaction vessel with a particular luminescent coating layer can easily be exchanged with a vessel having another luminescent coating layer so that the apparatus can be adapted to different wavelengths. The same is true for the quartz envelope, if it carries luminescent materials. ******If, on the other hand, the reaction vessel is brought to very low temperatures, for example, by filling it with liquid nitrogen, then in order to maintain a vacuum of approximately 10^-6 Torr in the intermediate space, the vessel and the quartz envelope must be fixedly fused together for sealing reasons. In that case, the substance or the solutions of substances are filled into separate quartz containers which are immersed in the liquid nitrogen, whereas the luminescent layer is applied to the inside of the outer quartz envelope in order to maintain the luminescent materials in a state of functional capability.[ because nitrogen balance the temperature of photochemical reactor and to produce vacum  ] THANK YOU VERY MUCH