Development of a compact laser-based heating stage for in situ spectroscopic characterizations

In this work, we present a recent advancement in high-temperature instrumentation in the form of a heating stage that enables studies to be performed in the temperature range of 20–1250°C under high-vacuum, millibar, and atmospheric pressure conditions (10⁻⁷–1000 mbar). The newly developed laser-based heating solution is described in detail. Its functionality is highlighted in this study in the form of a heating stage compatible with in situ ambient pressure X-ray photoelectron spectroscopy (APXPS). The proof-of-concept experiment presented in this work involves a polycrystalline nickel foil, a material of considerable interest in the scientific field due to its applications in catalysis, batteries, and electrochemistry. Owing to the intrinsic oxophilicity of nickel, the experiment targeted the high-temperature oxidation (600°C) and reduction (1050°C) that serves interest as both, a pretreatment and preparation method, and as a model reaction for the redox behavior of non-noble materials under reactive conditions. Complete and reversible surface state changes from metallic to oxide and back to metallic were achieved through stepwise variations of the gas phase composition and temperature. The heating stage showed high stability at high temperatures under reducing and oxidizing conditions, demonstrating the benefit of this design. The in situ characterization possibilities enabled by this stage will allow a better understanding of the inherent properties of materials that function at high temperatures, leading to their optimization in relevant application fields such as catalysis, materials, and surface science.