We present the design and implementation of a portable transfer system equipped with an integrated electrochemical cell that enables the controlled transfer of samples between an electrochemical environment and an ultrahigh vacuum (UHV) system without air exposure. This setup allows for the preparation of well-defined model surfaces, their electrochemical modification, and subsequent structural and chemical characterization using surface-sensitive UHV techniques. The system's performance was validated using Au(111) as a model electrode. Cyclic voltammetry performed in a hanging meniscus configuration reproduced the characteristic oxidation and reduction features of Au(111), while scanning tunneling microscopy, low-energy electron diffraction, and Auger electron spectroscopy confirmed the structural and chemical integrity of the surface after transfer. Progressive surface roughening with increasing numbers of oxidation-reduction cycles followed an approximately linear trend, consistent with previous studies. In addition, we investigated the stability of gold oxide under vacuum and demonstrated that the thin oxide formed during anodic polarization, prior to the onset of the oxygen evolution reaction, is partially reduced during UHV transfer. X-ray photoelectron spectroscopy and Auger spectroscopy data indicate that the oxidized phase is stable in vacuum only after polarization at sufficiently high potentials, when continuous oxygen evolution is achieved via water electrolysis. Finally, successful integration and testing of the system at the FlexPES beamline at MAX IV confirmed its compatibility with synchrotron-based spectroscopy.

Here we report an investigation of ultrathin tin oxide films on Pt3Sn(111) using low-energy electron microscopy (LEEM), microspot low-energy electron diffraction (μ-LEED), scanning tunneling microscopy (STM), surface X-ray diffraction (SXRD), and high-resolution X-ray photoelectron spectroscopy (XPS). Oxidation at ∼390–410 °C produces triangular, two-dimensional oxide islands that nucleate rapidly and exhibit self-limited lateral growth, attributed to limited Sn diffusion from the subsurface of the crystal. μ-LEED shows that the initially formed (4×4) Sn oxide is subsequently converted to a more oxygen-rich (2×2n) “stripe” phase. At 630 °C, enhanced Sn mobility enables a closed (4×4) film. The (2×2n) phase is shown to consist of a (2×2) Sn lattice modulated by 1D stripe defects with spacings of n=4–6 atomic rows; LEED and SXRD measurements show diffraction features corresponding to this striped superstructure. The two oxides can be distinguished in XPS by their O 1s lineshapes: the (4×4) phase shows a clear doublet attributable to distinct O species, whereas the (2×2n) phase exhibits a broader envelope consistent with a distribution of O coordination environments. The Sn 3d5/2 spectra are similar for both phases, reflecting closely related Sn bonding motifs. The spectra are consistent with those of previous near-ambient-pressure XPS measurements, suggesting that the surface oxides forming under CO oxidation conditions are similar to those studied here.