Galvez-Martinez Santos, Mateo-Marti Eva
Centro de Astrobiología (CSIC-INTA), Ctra. Ajalvir, Km. 4, 28850 Torrejón de Ardoz, Spain.
Life (Basel). 2018 Oct 25;8(4):50. doi: 10.3390/life8040050.
We characterized the adsorption of triglycine molecules on a pyrite surface under several simulated environmental conditions by X-ray photoemission spectroscopy. The triglycine molecular adsorption on a pyrite surface under vacuum conditions (absence of oxygen) shows the presence of two different states for the amine functional group (NH₂ and NH₃⁺), therefore two chemical species (anionic and zwitterionic). On the other hand, molecular adsorption from a solution discriminates the NH₂ as a unique molecular adsorption form, however, the amount adsorbed in this case is higher than under vacuum conditions. Furthermore, molecular adsorption on the mineral surface is even favored if the pyrite surface has been irradiated before the molecular adsorption occurs. Pyrite surface chemistry is highly sensitive to the chemical changes induced by UV irradiation, as XPS analysis shows the presence of Fe₂O₃ and Fe₂SO₄-like environments on the surface. Surface chemical changes induced by UV help to increase the probability of adsorption of molecular species and their subsequent concentration on the pyrite surface.
我们通过X射线光电子能谱表征了在几种模拟环境条件下三甘氨酸分子在黄铁矿表面的吸附情况。在真空条件（无氧）下，三甘氨酸分子在黄铁矿表面的吸附显示胺官能团（NH₂和NH₃⁺）存在两种不同状态，因此存在两种化学物种（阴离子型和两性离子型）。另一方面，从溶液中的分子吸附将NH₂识别为唯一的分子吸附形式，然而，这种情况下的吸附量高于真空条件下的吸附量。此外，如果在分子吸附发生之前对黄铁矿表面进行辐照，则分子在矿物表面的吸附甚至更有利。正如XPS分析表明表面存在Fe₂O₃和类Fe₂SO₄环境一样，黄铁矿表面化学对紫外线辐照引起的化学变化高度敏感。紫外线引起的表面化学变化有助于增加分子物种在黄铁矿表面吸附及其后续富集的概率。
