The role of semiconducting minerals in the prebiotic fixation of nitrogen and carbon

摘要

Much of the work focused on the photoreduction of carbon dioxide by iron(II) sulfide particles. Typical experiments consisted of irradiation of commercially available iron(II) sulfide powders in water at pH 7-8. Irradiation was broad band light, pyrex filtered, from a medium pressure mercury arc lamp. Preliminary results indicated the presence of trace organics in the solutions after irradiation. However, current results seem to indicate that contamination of the commercial powder is the course of those organics. It has also been decided that future experiments should focus on colloidal suspensions of iron(II) sulfide. Work also focused on the question of wether the Strecker synthesis can be carried out in the presence of iron(II). Typical experiments consisted of following the formation of glycine iminodiacetic acid as a function of time in a reaction mixture consisting of: CN(-1) (0.1M), iron(II) (either Fe(2), 0.1M, or FeS, 0.2g/ml), formaldehyde (0.1M), and NO2. In some cases iron(II) and nitrite were removed or ammonia was added as a control. Preliminary results showed that the Strecker synthesis is not poisoned by aqueous iron(II) or iron sulfide particles. Results also indicated the possibility of some catalytic effect in the Strecker synthesis. During this period, a paper entitled 'Experimental Results on the Prebiotic Fixation of Nitrogen Under a Neutral Atmosphere by Iron(II)' was presented at the First International Conference on Cirumstellar Habitable Zones. A paper entitled 'Prebiotic ammonia from reduction of nitrite by iron (II) on the early Eath' was published in Nature.