Chemical state

About: Chemical state is a research topic. Over the lifetime, 2378 publications have been published within this topic receiving 78183 citations.

Chemical State Analyses of Sulfur, Chromium and Tin by High Resolution X-Ray Spectrometry

Abstract: Chemical shifts of SKα, CrKβ1,3 and SnLβ2 were precisely measured with a two-crystal X-ray spectrometer (Toshiba AFV 701). Sulfur in the coke for iron smelting takes two oxidation states, i.e., S2− and S6+. Quantitative analyses of S2− and S6+ were performed by precisely measuring the profile of SKα and fitting the standard S2− of S6+ curve to the observed SKα profile with the non-linear least square method. Chemical shifts of CrKβ1,3 and SnLβ2 were utilized for the determinations of Cr6+, Cr3+, Sn4+ and Sn2+ in electro-plating solutions. Intensity ratio of IA to Ig was measured, where B means the point which showed an intensity independent of oxidation states. A means the point which showed the most dependent. Linear relations were found between intensity ratio IA/IB and Cr3+/Cr or Sn2+/Sn.

Electron spectroscopic study of C–N bond formation by low-energy nitrogen ion implantation of graphite and diamond surfaces

Abstract: The effect of 500 eV N2+ irradiation of graphite and diamond surfaces has been investigated by in situ electron spectroscopies (Auger electron spectroscopy and x-ray photoelectron spectroscopy). The chemical state of the implanted nitrogen and carbon have been studied as a function of: (i) implantation temperature in the room temperature (RT) to 800 K range, (ii) annealing of the RT implanted layer up to 800 K, (iii) and ion dose. It is concluded that the implanted nitrogen is present in three different bonding states, denoted as α, β, and γ, for all implantation conditions. The distribution of these states was found to be affected by the substrate nature as well as by the temperature of implantation and annealing process. A chemical interconvertion model is proposed to explain the changes in population of the carbon–nitrogen bonding states as a function of annealing and implantation temperature. It is suggested that the β state includes nitrogen atoms in threefold configurations and may be related to an ...

Determination of the structure of GaAs(100)-S with chemical-state-specific photoelectron diffraction.

Abstract: The chemical passivation of a semiconductor surface is an important step in electronic device manufacturing. This paper describes the application of chemical-state-specific photoelectron diffraction to solve the surface structure of sulfur-passivated GaAs(100). The results show that the GaAs(100)-S surface is terminated with ordered Ga-S-Ga bridge bonds in the [011] azimuth, and on top of this is a disordered arsenic sulfide overlayer. Complex surface structure such as GaAs(100)-S would not be resolved with conventional techniques such as low-energy electron diffraction, x-ray-absorption near-edge structure, surface-extended x-ray-absorption fine-structure, or vibrational spectroscopies

Modifying electronic properties at the silicon-molecule interface using atomic tethers

Abstract: The electronic properties at the semiconductor–molecule interface can be altered by changing the nature of covalent attachment. We examine the change in work function of the silicon surface after formation of Si–O–C, Si–C–C, and Si–S–C bonded alkyl monolayers and separate charge transfer and dipolar contributions. The chemical state, monolayer structure, and electronic properties of aliphatic monolayers with oxygen, carbon, and sulfur covalent linkages to the Si(1 1 1) surface were investigated with contact angle wetting, spectroscopic ellipsometry, infrared vibrational spectroscopy, X-ray photoemission spectroscopy, and ultraviolet photoemission spectroscopy. Vibrational spectra indicate aliphatic films tethered to Si with few gauche defects in agreement with hydrophobic contact angles and ellipsometric thickness measurements. Core level electronic spectra taken as a function of semiconductor doping reveal shifts in binding energy attributed to molecular bonding. Valence band spectra reveal the work function of the molecule–Si composite as a function of semiconductor doping and atomic tether. By combining valence band spectra with core level spectra, the electronic properties of the molecule–Si system can be understood. In particular, the relative contribution of charge transfer due to surface band bending and the polarization due to molecular dipoles were determined. The O, C, and S atomic tethers induce differing amounts of band bending and interface dipoles which can be utilized to engineer the electronic properties of molecule–semiconductor junctions.