The Infrared Absorption Spectra of Nickel Metal Surfaces Modified with Optically Active α-Alanine from Its Aqueous Solution

Abstract

The infrared absorption spectra of thin films of α-alanine formed on pure nickel and “Raney nickel” surfaces, modified with its aqueous solution, were measured by the high-sensitivity reflection method. From the infrared dichroism in the reflection spectra, the molecular orientations in the thin films were derived. In the thin film formed on pure nickel modified at 5 °C, the CO2− group of α-alanine is oriented nearly vertical to the metal surface and the O···O axis is inclined to the surface. On the other hand, when the “Raney nickel” film is modified at 5 °C, the Cα–Co(carboxylate) bond is oriented obliquely to the surface. When the “Raney nickel” film is modified at 100 °C, the Ni-alanine chelate is formed on the surface: the Cα–Co bond and the NH2 group are nearly parallel to the substrate surface, while the O···O axis is vertical to that surface.

Solvent effect on CO oxidation as a novel diagnosing tool to pin down low-coverage CO at the liquid–solid interface: An in situ infrared study

“…RAIRS is typically applied in ultrahigh vacuum [19,20] and electrochemical [21,22] settings to probe vacuum-solid and liquid-solid interfaces, respectively. It can also be used ex situ to characterize organic adsorbates exposed to ambient air [23,24], but RAIRS studies in the presence of organic solvents under non-electrochemical conditions are scarce. Inspired by the observations that some carbonyl compounds may decompose on metal catalysts under catalytic conditions [25][26][27], we systematically investigated the interaction of several categories of organics with polycrystalline Pt by in situ RAIRS [28].…”