Room-Temperature Reaction of Oxygen with Gold: An In situ Ambient-Pressure X-ray Photoelectron Spectroscopy Investigation

AbstractIonizing radiation damage to DNA plays a fundamental role in cancer therapy. X-ray photoelectron-spectroscopy (XPS) allows simultaneous irradiation and damage monitoring. Although water radiolysis is essential for radiation damage, all previous XPS studies were performed in vacuum. Here we present near-ambient-pressure XPS experiments to directly measure DNA damage under water atmosphere. They permit in-situ monitoring of the effects of radicals on fully hydrated double-stranded DNA. The results allow us to distinguish direct damage, by photons and secondary low-energy electrons (LEE), from damage by hydroxyl radicals or hydration induced modifications of damage pathways. The exposure of dry DNA to x-rays leads to strand-breaks at the sugar-phosphate backbone, while deoxyribose and nucleobases are less affected. In contrast, a strong increase of DNA damage is observed in water, where OH-radicals are produced. In consequence, base damage and base release become predominant, even though the number of strand-breaks increases further.

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In situ investigation of degradation at organometal halide perovskite surfaces by X-ray photoelectron spectroscopy at realistic water vapour pressure

Chemical Communications ◽

10.1039/c7cc01538k ◽

2017 ◽

Vol 53 (37) ◽

pp. 5231-5234 ◽

Cited By ~ 37

Author(s):

Jack Chun-Ren Ke ◽

Alex S. Walton ◽

David J. Lewis ◽

Aleksander Tedstone ◽

Paul O'Brien ◽

...

Keyword(s):

Water Vapour ◽

Photoelectron Spectroscopy ◽

Ambient Pressure ◽

Water Vapour Pressure ◽

Lead Iodide ◽

X Ray ◽

In Situ Investigation ◽

Organometal Halide Perovskite ◽

Methylammonium Lead Iodide

Near-ambient-pressure X-ray photoelectron spectroscopy enables the study of the reaction of in situ-prepared methylammonium lead iodide (MAPI) perovskite at realistic water vapour pressures for the first time.

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An in situ near-ambient pressure X-ray Photoelectron Spectroscopy study of Mn polarised anodically in a cell with solid oxide electrolyte

Electrochimica Acta ◽

10.1016/j.electacta.2015.05.173 ◽

2015 ◽

Vol 174 ◽

pp. 532-541 ◽

Cited By ~ 11

Author(s):

Benedetto Bozzini ◽

Matteo Amati ◽

Patrizia Bocchetta ◽

Simone Dal Zilio ◽

Axel Knop-Gericke ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Ambient Pressure ◽

Solid Oxide ◽

Spectroscopy Study ◽

Solid Oxide Electrolyte ◽

X Ray ◽

A Cell ◽

Oxide Electrolyte

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Characterization of Ti/SnO2 Interface by X-ray Photoelectron Spectroscopy

Nanomaterials ◽

10.3390/nano12020202 ◽

2022 ◽

Vol 12 (2) ◽

pp. 202

Author(s):

Miranda Martinez ◽

Anil R. Chourasia

Keyword(s):

Photoelectron Spectroscopy ◽

Room Temperature ◽

Chemical Interaction ◽

Photoelectron Spectra ◽

X Ray ◽

Increasing Trend ◽

Substrate Temperatures ◽

Beam Technique

The Ti/SnO2 interface has been investigated in situ via the technique of x-ray photoelectron spectroscopy. Thin films (in the range from 0.3 to 1.1 nm) of titanium were deposited on SnO2 substrates via the e-beam technique. The deposition was carried out at two different substrate temperatures, namely room temperature and 200 °C. The photoelectron spectra of tin and titanium in the samples were found to exhibit significant differences upon comparison with the corresponding elemental and the oxide spectra. These changes result from chemical interaction between SnO2 and the titanium overlayer at the interface. The SnO2 was observed to be reduced to elemental tin while the titanium overlayer was observed to become oxidized. Complete reduction of SnO2 to elemental tin did not occur even for the lowest thickness of the titanium overlayer. The interfaces in both the types of the samples were observed to consist of elemental Sn, SnO2, elemental titanium, TiO2, and Ti-suboxide. The relative percentages of the constituents at the interface have been estimated by curve fitting the spectral data with the corresponding elemental and the oxide spectra. In the 200 °C samples, thermal diffusion of the titanium overlayer was observed. This resulted in the complete oxidation of the titanium overlayer to TiO2 upto a thickness of 0.9 nm of the overlayer. Elemental titanium resulting from the unreacted overlayer was observed to be more in the room temperature samples. The room temperature samples showed variation around 20% for the Ti-suboxide while an increasing trend was observed in the 200 °C samples.

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Carbide-Modified Pd on ZrO2 as Active Phase for CO2-Reforming of Methane—A Model Phase Boundary Approach

Catalysts ◽

10.3390/catal10091000 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1000

Author(s):

Norbert Köpfle ◽

Kevin Ploner ◽

Peter Lackner ◽

Thomas Götsch ◽

Christoph Thurner ◽

...

Keyword(s):

Phase Boundary ◽

Photoelectron Spectroscopy ◽

Batch Reactor ◽

Ambient Pressure ◽

Composite Layer ◽

Reaction Rates ◽

Near Surface ◽

X Ray ◽

Zro2 Phase

Starting from subsurface Zr0-doped “inverse” Pd and bulk-intermetallic Pd0Zr0 model catalyst precursors, we investigated the dry reforming reaction of methane (DRM) using synchrotron-based near ambient pressure in-situ X-ray photoelectron spectroscopy (NAP-XPS), in-situ X-ray diffraction and catalytic testing in an ultrahigh-vacuum-compatible recirculating batch reactor cell. Both intermetallic precursors develop a Pd0–ZrO2 phase boundary under realistic DRM conditions, whereby the oxidative segregation of ZrO2 from bulk intermetallic PdxZry leads to a highly active composite layer of carbide-modified Pd0 metal nanoparticles in contact with tetragonal ZrO2. This active state exhibits reaction rates exceeding those of a conventional supported Pd–ZrO2 reference catalyst and its high activity is unambiguously linked to the fast conversion of the highly reactive carbidic/dissolved C-species inside Pd0 toward CO at the Pd/ZrO2 phase boundary, which serves the role of providing efficient CO2 activation sites. In contrast, the near-surface intermetallic precursor decomposes toward ZrO2 islands at the surface of a quasi-infinite Pd0 metal bulk. Strongly delayed Pd carbide accumulation and thus carbon resegregation under reaction conditions leads to a much less active interfacial ZrO2–Pd0 state.

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