Topic
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 article, the molecular orientation and electronic structure of 11,11,12,12-tetracyanonaphtho-2,6-quinodimethane (TNAP) vacuum-deposited on various metal substrates (Au, Ag, and Cu evaporated films) were studied in situ by IR-RAS, UV photoemission spectroscopy (UPS), and density functional theory calculations.
Abstract: The molecular orientation and electronic structure of 11,11,12,12-tetracyanonaphtho-2,6-quinodimethane (TNAP) vacuum-deposited on various metal substrates (Au, Ag, and Cu evaporated films) were studied in situ by infrared reflection-absorption spectroscopy (IR-RAS), UV photoemission spectroscopy (UPS), and density functional theory calculations. The molecular orientation and the electronic structures were studied by IR-RAS and UPS, respectively, and the chemical states were deduced by the combination of these methods, with the aid of theoretical simulation. TNAP molecules on Au were found to be almost completely flat lying in the neutral state. At the initial stage of deposition on a Ag substrate, electron transfer from the substrate takes place, leading to the formation of TNAP anion. The UPS spectra for this film also corresponded well with the theoretical simulation of an anion. Upon further deposition, the upper layer becomes neutral, with flat-lying orientation but not completely as in the film on Au...
12 citations
TL;DR: In this article, the outermost layer of gold nanorods was studied using XPS spectroscopy and ab initio calculations to compare the chemical states of the constituents of the metallic core.
Abstract: In this manuscript, we prepared gold nanorods (Au-NRs) through “silver-assisted seeded methodology” and studied their outermost layer using XPS spectroscopy and ab initio calculations to compare the chemical states of the constituents of the metallic core. Supporting first-principles calculations employing a relativistic, full-potential and all-electron method, with augmented plane waves plus local orbitals as a basis set, ensure proper treatment of the core electron states. Three significant findings can be reported. First, we found that besides Au (0), there are two chemical states for silver, namely Ag (0) and Ag(I), on the Au surface. Our results corroborate with recent results reported in the literature, indicating that Ag monolayer can be oxidized to Ag(I) during the steps of centrifugation and washing with diluted CTAB solution. Second, ab initio simulations showed that Ag atoms have different binding energies, depending on their configuration in Au-NRs (whether silver atoms are found on the surface or if they are spread in bulk as interstitial or substitutional defects). Third, theoretical studies showed that silver atoms located at interstitial sites could distort the crystalline structure, and, therefore, we do not expect interstitial Ag to occur in Au-NRs.
12 citations
09 Sep 1994
TL;DR: In this article, a-C:H/W composites of tungsten and chromium containing hydrogenated amorphous carbon films were evaluated using X-ray Photoelectron Spectroscopy (XPS).
Abstract: Tungsten and chromium containing hydrogenated amorphous carbon films were deposited in a process which combines plasma activated chemical vapor deposition of methane and r.f.- sputtering of a metallic target. The metal content of the deposits can be adjusted by the ratio of gas flow between argon and methane and was determined by X-ray Photoelectron Spectroscopy (XPS). For the a-C:H/W composites the XPS data are presented in detail and supply information about the chemical state of carbon and tungsten. The presence of W in carbidic state could be proven. Furthermore the optical constants n and k of a-C:H/W were obtained in the wavelength range between 0.4 and 2.6micrometers and for W concentrations of up to 33 at.%. The morphology of the deposits, determined by atomic force microscopy, ranges from very porous to compact and can be controlled by the substrate bias voltage. Accelerated ageing investigations were performed in air in order to characterize the deterioration mechanisms of a-C:H/W and a-C:H/Cr films deposited on different substrate materials. The significance of the morphology of the coating and the roughness of the substrate for the ageing mechanisms could be shown. Very promising results concerning the film stability were obtained for a-C:H/Cr.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
12 citations
TL;DR: In this article, a thermodynamic study has been carried out to predict the possible transformations of the iron-cobalt alloys when contacted with CO-CO 2 mixtures between 700 and 900 K. The stability domains of the different solid phases were determined taking into account the nonideal character of these alloys.
12 citations
TL;DR: In this paper, the depth profiles of chemical states of alloying elements (Cr and Fe) were measured in the oxide layer of Zr-0.5Sn-1.0Cr- 0.5Fe alloys.
12 citations