Inelastic electron tunnelling spectroscopy—V. The formation of molecules of bioevolutionary importance on an alumina surface

Abstract

The alumina barrier of AlAlO x Pb tunnelling junctions have been exposed to aqueous ammonia, wet carbon monoxide gas and to aqueous formaldehyde vapour. The aqueous ammonia spectrum is assigned as an amino acid species produced from ammonia, water and atmospheric carbon dioxide. This spectrum fingerprints very closely with the tunnelling spectrum of a genuine sample of glycine. The role of atmospheric carbon dioxide is deduced from a spectrum of aqueous ammonia produced in the absence of carbon dioxide. The wet carbon monoxide spectrum and the aqueous formaldehyde spectrum have been produced by an infusion doping process. These spectra are assigned as a sugar-like polymer or a sugar formed on the alumina surface. A tunnelling spectrum of d(−)fructose has been produced to aid this assignment. The role of an inorganic template such as alumina in the original prebiotic synthesis of amino acids and sugars is considered.