The Role of Semiconducting Minerals in the Prebiotic Fixation of Nitrogen and Carbon

摘要

Biochemical compounds are made up largely of relatively reduced carbon and nitrogen. Today, these compounds are produced biogenically. Most theories for the origins of life depend on the synthesis of reduced carbon/nitrogen compounds from which self-replicating molecules, membranes, or surface metabolites can arise. Thus abiotic sources of such compounds are crucial to such theories. In a reducing atmosphere, electric discharges are sufficient for the fixation of both carbon and nitrogen. However, geochemical evidence seems to point to a non-reducing atmosphere composed of CO2, N2, and H2O. In such a neural atmosphere, shock heating produces NO and CO. Carbon dioxide and dinitrogen are relatively oxidized forms of carbon and nitrogen. They are also, especially for nitrogen, among the less reactive forms. Processes for the prebiotic synthesis of the 'starting materials' of life need to accomplish two feats. One, supply a source of reducing equivalents, and two, overcome the low reactivity of carbon dioxide and dinitrogen.