RESUMO
The study of surface properties at the nanoscale plays a crucial role in material science applications. This paper demonstrates the capabilities of Auger PhotoElectron Coincidence Spectroscopy (APECS) to obtain data with varying surface sensitivities from a single measurement. This makes it possible to extract the spectrum from the outermost surface layer even when faced with strongly overlapping surface and bulk spectral features, which we demonstrate by accurately extracting the surface component in Au 4f photoemission. Leveraging high energy resolution, transmission efficiency, tunable photon energy, and remarkable surface sensitivity of the APECS setup, we propose that optimal experimental conditions can be tailored to determine surface spectra accurately for a diverse range of materials. This opens new avenues for advancing our understanding of nanoscale surface phenomena across various material systems.
RESUMO
Commercial use of lead halide perovskites requires improved thermal stability and therefore a better understanding of their degradation mechanisms. The thermal degradation of three clean perovskite single crystal surfaces (MAPbI3, MAPbBr3, FAPbBr3) was investigated using synchrotron-based photoelectron spectroscopy. Central findings are that the halide has a large impact on thermal stability and that the degradation of formamidnium results in the formation of a new organic species at the FAPbBr3 crystal surface.