Adsorption of Water, Methanol, and Formic Acid on Fe2NiP, a Meteoritic Mineral Analogue

The surface of an analogue to the meteoritic mineral schreibersite or (Fe,NO)(3)P was investigated to provide insight into the interaction of the mineral surface with prebiotic molecules such as water, methanol, and formic acid. A protocol for creating synthetic metal-phosphide samples with a surface reflectivity suitable for reflection absorption infrared spectroscopy (RAIRS) was developed and is outlined in this paper. Scanning electron microscopy coupled with energy dispersive spectroscopy revealed an average defect size less than 1 mu m and evidence of subsurface phosphorus segregation. At surface temperatures between 120 and 140 K, RAIRS spectra indicate that water and formic acid interact molecularly with surface atoms, while methanol appears to dissociate into methoxy and protons upon adsorption. The observed infrared spectra provide insight into the adsorption geometries of these prebiotic molecules on synthetic schreibersite. This data suggests the importance of the schreibersite mineral surface in aqueous-phase schreibersite-mediated phosphorylation experiments that have been performed by others and strengthens the argument that schreibersite-induced chemistry could, Occur in astrochemical environments.