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Chemical state
About: Chemical state is a research topic. Over the lifetime, 2378 publications have been published within this topic receiving 78183 citations.
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TL;DR: In this paper, spectroscopic evidence of π-conjugated polymer formation at the interface between an iodine-modified Au(111) and an aqueous solution was presented.
Abstract: On-surface polymerization realized at the solid–liquid interface represents a promising route to obtain stable and conductive organic layers with tunable properties. We present here spectroscopic evidence of π-conjugated polymer formation at the interface between an iodine-modified Au(111) and an aqueous solution. Schiff-base coupling has been used to drive the reaction by changing the pH. Scanning tunneling microscopy (STM) investigations show that the substrate acts as a template driving the formation of 1D ordered nanostructures. All the chemical states of the molecules on the surface have been identified and their evolution as a function of the pH has been monitored by synchrotron radiation X-ray photoelectron spectroscopy (XPS), demonstrating that two polymeric phases, undistinguishable by STM, exist on the surface: intermediate state and π-conjugated final product. The I/Au(111) substrate enhances the formation of π-conjugated polymers, as established comparing their production on the surface and in...
33 citations
TL;DR: In this article, low-energy Ar+-induced modifications of III-V semiconductor (110) surfaces have been investigated and the actual composition of the sputtered surfaces has been determined by either the elemental standard method or normalization to the cleaved surface signals.
Abstract: Low-energy Ar+-induced modifications of III–V semiconductor (110) surfaces have been investigated. XPS, angle-resolved AES and Auger profiles have been used to check the in-depth composition over the range of tens to hundreds of angstroms. The actual composition of the sputtered surfaces has been determined by either the elemental standard method or normalization to the cleaved surface signals. Auger and XPS lineshape analysis and EELS spectra provided information on the chemical state of the components in the sputter-altered region.
GaAs and InP surfaces have been found to be metal enriched, the enrichment being larger at high ion beam energy. The 5 keV Ar+bombardment of the cleaved InP target results in the steady-state composition In(67)P(33) at the surface. The composition is graded in the subsurface region up to the stoichiometric value In(50)P(50). Although the sputter-altered GaAs region can be depicted roughly as As-depleted, the As concentration is larger at the surface than in the subsurface region. The surface ‘spike’ and the subsurface ‘dip’ in the As concentration strongly depend on the ion beam energy in terms of both the intensity and the extension in depth. These results indicate that As radiation-enhanced Gibbsian segregation and P preferential sputtering are the dominant mechanisms of surface modification in GaAs and InP, respectively.
32 citations
TL;DR: In this paper, the nature of copper species of a series of alumina-supported copper samples was investigated by the kinetics of reduction, x-ray photoelectron spectroscopy, temperature-programmed desorption-mass spectrometry of chemisorbed NO and infrared spectroscopic analysis of CO and CO probes.
Abstract: The nature of copper species of a series of alumina-supported copper samples was investigated by the kinetics of reduction, x-ray photoelectron spectroscopy, temperature-programmed desorption-mass spectrometry of chemisorbed NO and infrared spectroscopy of chemisorbed NO and CO probes. The role of these copper species was also examined in the catalytic decomposition of NO. The surface properties of copper were found to depend strongly on both Cu loading and calcination treatment
32 citations
TL;DR: In this paper, a high-energy resolution crystal spectrometer in Johansson geometry, which allows energy resolution below the natural linewidth of the Ka diagram lines, was employed in the measurements of proton-induced Ka x-ray emission spectra of titanium and sulfur pure and compound targets.
Abstract: A high-energy resolution crystal spectrometer in Johansson geometry, which allows energy resolution below the natural linewidth of the Ka diagram lines, was employed in the measurements of proton-induced Ka x-ray emission spectra of titanium and sulfur pure and compound targets. The results demonstrate a clear dependence of the Ka energy shifts on the chemical state of the element in the sample. This dependence permits the chemical state speciation of low-Z elements in an unknown sample by employing high-resolution PIXE measurements of the Ka line. The potential of the technique in speciation studies is demonstrated in the case of an aerosol sample. The analysis of the Ka line obtained from the high-energy resolution proton-induced S Ka x-ray spectrum allowed the identification of sulfur in the aerosol sample as sulfate ([SO 4 ] 2- ).
32 citations
TL;DR: In this article, different chemical reactions involving the chemical state of oxygen and nitrogen are shown to occur with different products and rates depending on the peculiar way of energy deposition in PMDA-ODA, and thermal treatment results in the formation of large condensed aromatic systems, possible precursors for true graphitization at higher termperature.
Abstract: Chemical reactions induced by heat and particle bombardment at low energy in PMDA-ODA were studied by XPS and REELS. Different chemical reactions involving the chemical state of oxygen and nitrogen are shown to occur with different products and rates depending on the peculiar way of energy deposition. In particular, thermal treatments proceed mainly by decarbonylation of imidic rings, leaving the ether linkage in the PMDA-ODA unit essentially unaffected. Evidence is found that thermal treatment results in the formation of large condensed aromatic systems, possible precursors for true graphitization at higher termperature
32 citations