Chapter Four · failure evidence
What X-Ray Photoelectron Spectroscopy (XPS) got wrong, from 16 dissertations
The records document experimental failures and methodological limitations encountered when applying X-ray photoelectron spectroscopy. Key difficulties include sample charging, beam and vacuum induced degradation, sputtering depth profiling limits, adventitious contamination, and core level peak overlaps. These records come from PhD theses at 9 institutions, 2021 to 2026. Each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.
Electrostatic sample charging distorts spectra and prevents acquisition on insulating materials
Severe sample charging and loss of conductivity prevented spectral acquisition on thick battery interphases and solid composite electrolytes despite charge neutralization. Differential charging on porous oxide layers produced severe peak distortions and abnormal binding energy positions.
Tried and failed
X-ray photoelectron spectroscopy surface characterization applied to thick insulating cycled battery interphases. Outcome: no signal. Reason: Severe sample charging and loss of electronic conductivity prevented spectral acquisition.
Tried and failed
High-resolution X-ray photoelectron spectroscopy applied to porous metal oxide layers. Outcome: no signal. Reason: Severe peak distortion and abnormal positions caused by differential surface charging on porous oxide layers
Kinetics and heat transfer during crystallization of gas hydrates and ice · UT Austin
Tried and failed
synchrotron x-ray photoelectron spectroscopy with charge neutralization applied to insulating solid polymer-ceramic composite electrolytes. Outcome: no signal. Reason: severe sample charging effects persisted despite conductive bridging and charge neutralizers
Understanding Ion Conduction in Polymer-Ceramic Composite Electrolytes for Lithium Ion Batteries · MIT
Vacuum conditions and beam exposure cause sample degradation and volatilization
Ultra-high vacuum and electron beam exposure caused artifactual cation reduction in transition metal oxides as well as degradation and metallic lead segregation in perovskites. Volatile surface species on fluorinated organic powders also volatilized under ultra-high vacuum and risked instrument contamination.
Tried and failed
X-ray photoelectron spectroscopy with charge neutralization applied to high-valence transition metal oxides. Reason: High vacuum and flood gun electron beam exposure caused artifactual reduction of reducible transition metal cations
Redox stability and ionic conduction in donor-substituted LaNbo4 under hydrogen environments · Imperial
Tried and failed
X-ray photoelectron spectroscopy surface characterisation applied to fluorinated organic powder surfaces. Outcome: unstable. Reason: Surface species volatilised under ultra-high vacuum, risking instrument contamination.
Surface properties and the manufacturability of fine pharmaceutical powders · Imperial
Tried and failed
time-resolved photoemission spectroscopy under vacuum applied to hybrid organic-inorganic lead halide perovskites. Outcome: unstable. Reason: Severe beam- and vacuum-induced sample degradation and metallic lead segregation occurred at the surface.
Time- and Angle-Resolved Photoelectron Spectroscopy of Solar Materials · EPFL
Left open by the authors
Problems the authors named and did not get to.
Left open
Perform XPS compositional analysis on the <2 µm redeposition layer to identify valence states and the origins of excess oxygen and fluorine. Blocker: Requires physical etched samples and an XPS (X-ray photoelectron spectroscopy) lab apparatus.
Atmospheric pressure plasma etching of Ti-6Al-4V using SF₆ · Cranfield
Left open
Investigate the 10 ms to 10 s slow decay in v-Ta2O5 to determine if it is a secondary relaxation linked to Brownian noise. Blocker: Requires experimental X-ray photon correlation spectroscopy (XPCS) or specialized experimental data on v-Ta2O5 samples.
X-ray induced temperature dependent amorphous-amorphous transitions in the GeO2 glass · IRIS - UNITN - prod
Left open
Perform XPS measurements on scraped and pressed powders from nickel films to eliminate surface oxidation artifacts. Blocker: Requires a physical materials lab, nickel film samples, and an XPS apparatus
Left open
Investigate palladium oxidation and reduction intermediate states and processes in natural gas three-way catalysts using X-ray absorption spectroscopy (XAS). Blocker: Requires synchrotron X-ray absorption spectroscopy (XAS) physical facilities and wet lab catalyst synthesis/testing setups.
Left open
Perform TEM-EDS elemental mapping to determine the distribution and dispersion of Ce and Mn species in the catalyst materials. Blocker: Requires access to synthesized catalyst samples and transmission electron microscopy energy-dispersive X-ray spectroscopy (TEM-EDS) instruments.
Selective oxidation catalysis over manganese and tungsten based oxide catalysts · Imperial
Left open
Combine electrochemical measurements of catalyst oxidation with FTIR, STM, HRTEM, and X-ray absorption spectroscopy. Blocker: Requires advanced physical characterization instruments and wet-lab electrochemical experimental facilities (FTIR, STM, HRTEM, XAS)
Electrochemical studies of carbon monoxide oxidation on platinum and platinum based fuel cell catalysts · Texas Tech
Left open
Use X-ray photoelectron spectroscopy to measure Fe2+/Fe3+ atomic ratios and identify ligands that increase Fe solubility in piperazine solutions. Blocker: Requires physical laboratory samples and an X-ray photoelectron spectroscopy (XPS) apparatus.
Mitigation methods for piperazine oxidation in post-combustion carbon capture · UT Austin
Left open
Conduct EXAFS measurements on the synthesized catalyst to verify the 5-coordination Pt structure following CO insertion. Blocker: Requires a synchrotron radiation facility / X-ray absorption spectroscopy beamline and physical catalyst samples
Left open
Perform X-ray photoelectron spectroscopy on Ag57- nanoclusters to confirm their mixed-valence electronic state. Blocker: Requires synthesized Ag57- nanocluster samples and an X-ray photoelectron spectroscopy (XPS) instrument.
Left open
Investigate heterogeneous electrochemical and chemo-mechanical degradation at cathode-electrolyte interfaces using in-operando X-ray fluorescence microscopy combined with X-ray absorption spectroscopy. Blocker: Requires synchrotron beamline facilities, specialized in-operando XFM/XAS instrumentation, and physical thin-film solid-state battery samples.
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