Iron-nickel phosphides may have been the source of reactive phosphorus for prebiotic chemistry on the Early Earth. Experiments in aqueous solution confirm that metal phosphides, found primarily in iron meteorites, can phosphorylate building block molecules (e.g., glycerol, choline and nucleosides). However, the process of phosphorus release from the mineral surface has not been identified, and it is unclear whether phosphorylation is a surface-mediated process. To better understand the specific role of iron-nickel phosphide surfaces in phosphorylation of small organics, synthetic Fe<sub>3</sub>P and Fe<sub>2</sub>NiP samples have been studied using surface science methods. Solid samples have been prepared from powders by pressing them into a pellet, sintering under an inert argon atmosphere, and polishing to a mirror finish. Surface characterization has been performed via scanning tunneling microscopy with electron backscattering (SEM/EDX) to determine the elemental composition of the surface, identify any potential contaminants, and confirm that geometric surface defects are generally less than 1 micron. The interaction of water, methanol and formic acid with these synthetic metal phosphide samples have then been analyzed by reflection absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TPD) in an ultrahigh vacuum chamber. The spectra provide information about the variety and strength of potential binding sites on the iron-nickel phosphide surface. To our knowledge, these spectra are also the first example of RAIRS on a metal phosphide.

Surface characterization of iron-nickel phosphides to understand their role in prebiotic phosphorylation

251st National Meeting (2016)

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