Index of content:
Volume 23, Issue 1, June 2016
23(2016); http://dx.doi.org/10.1116/1.4943099View Description Hide Description
Cellulose and lignin reference samples have been investigated to enable the easier identification of the composition of pine wood strands in XPS. Presented here are the survey and high resolution x-ray photoelectron spectra of cellulose and lignin. Cellulose is characterised by a lack of intensity of the aliphatic carbon peak in addition to an intense carbon-oxygen peak corresponding to alcohols groups. Lignin is characterised by the presence of an intense aliphatic peak and a π-π* shake-up.
23(2016); http://dx.doi.org/10.1116/1.4948526View Description Hide Description
Switchable ionic liquids (SWIL) play an important role in green chemistry. Due to the nature of SWIL chemistry, such as air sensitivity, pressure, and temperature dependence, it is difficult to characterize SWIL using vacuum-based surface techniques. The fully CO2 loaded 1:1 mixtures of 1,8-diazabicycloundec-7-ene (DBU) and 1-hexanol (a SWIL system) and non-CO2 loaded DBU and 1-hexanol mixture were analyzed by in situ time-of-flight secondary ion mass spectrometry (ToF-SIMS) coupled with the system for analysis at the liquid vacuum interface (SALVI), respectively. The DBU/1-hexanol/CO2 SWIL was injected into the microchannel before liquidsecondary ion mass spectrometryanalysis. Bi3+ primary ion beam was used. The positive and negative spectra of the SWIL chemical components are presented. The characteristic peaks m/z 153 (protonated DBU) in the positive mode and m/z 101 (deprotonated 1-hexanol) in the negative mode were observed. In addition, ion pair peaks including m/z 253, 319, 305, and 451 in the positive mode and m/z 145, 223, and 257 in the negative mode are first observed using this approach. These results demonstrate that the SALVI microfluidic reactor enables the vacuum-based surface technique (i.e., ToF-SIMS) for in situ characterization of challenging liquid samples such as ionic liquids.
23(2016); http://dx.doi.org/10.1116/1.4953792View Description Hide Description
Silver nanoparticles of many types are widely used in consumer and medical products. The surface chemistry of particles and the coatings that form during synthesis or use in many types of media can significantly impact the behaviors of particles including dissolution, transformation and biological or environmental impact. Consequently it is useful to be able to extract information about the thickness of surface coatings and other attributes of nanoparticles produced in a variety of ways. It has been demonstrated that X-ray Photoelectron Spectroscopy (XPS) can be reliably used to determine the thickness of coatings and shells. However, care is required to produce reliable and consistent information. Here we report XPS spectra from gold/silver core-shell nanoparticles of nominal size 20 nm removed from a citrate saturated solution after one washing cycle. The Simulation of Electron Spectra for Surface Analysis (SESSA) program has been used to model peak amplitudes to obtain information on citrate coatings that remain after washing and demonstrate the presence of the gold core. This data is provided in digital form so that others can compare use of SESSA or other modeling approaches to quantify the nature of coatings to those already published and to explore the impacts particle non-uniformities on XPS signals from core-shell nanoparticles.
XPS examination of the native oxide layer on Kovar using aluminium, magnesium and silver x-ray sources23(2016); http://dx.doi.org/10.1116/1.4954179View Description Hide Description
Kovar, a common glass-to-metal sealing alloy, has been analysed by XPS. Monochromatic aluminium and silver sources as well as an achromatic magnesium x-ray source have been utilised to demonstrate the increased clarity of spectra that can be obtained through the use of each x-ray source in the analysis of a transition metal rich alloy.
23(2016); http://dx.doi.org/10.1116/1.4954192View Description Hide Description
Infrared to ultraviolet range ellipsometric spectra of thin film silicon nitride (SiNx) collected from rotating compensator instruments have been analyzed simultaneously. A common complex dielectric function (ε = ε 1 + iε 2) parameterization from 0.08 to 5.89 eV for amorphous 490 Å thick low pressure chemical vapor deposition SiNx, nominally x = 1.33 Si3N4, on a single crystal silicon (c-Si) wafer is determined. Visible to ultraviolet range electronic transitions at high photon energies and infrared active vibrational modes at low energies are identified.
Eagle XG® glass, optical constants from 230 to 1690 nm (0.73 - 5.39 eV) by spectroscopic ellipsometry23(2016); http://dx.doi.org/10.1116/1.4954226View Description Hide Description
Eagle XG® glass is widely used in the manufacture of electronic displays. Spectroscopic ellipsometry and transmission data for this material were obtained from 193 to 1690 nm. The optical constants of the material were then modeled from 230 to 1690 nm. The data were initially fit with a basis spline (B-spline), and these results were used as the starting point for either a two-Gaussian oscillator model or a Tauc-Lorentz (T-L) + Gaussian oscillator model. Both models gave good fits, with unweighted mean squared error values of ca. 1.1. Samples were provided by Corning Incorporated directly from their production facility.
23(2016); http://dx.doi.org/10.1116/1.4954387View Description Hide Description
Fe2O3 nanodeposits have been grown on fluorine-doped tin oxide (FTO) substrates by plasma enhanced-chemical vapor deposition (PE-CVD). Subsequently, the obtained systems have been functionalized through the sequential introduction of TiO2 and Au nanoparticles (NPs) by means of radio frequency (RF)-sputtering. The target nanocomposites have been specifically optimized in view of their ultimate functional application in solar-driven H2 generation. In the present study, our attention is focused on a detailed X-ray photoelectron spectroscopy (XPS) characterization of the surface composition for a representative Fe2O3-TiO2-Au specimen. In particular, this report provides a detailed discussion of the analyzed C 1s, O 1s, Fe 2p, Ti 2p, and Au 4f regions. The obtained results point to the formation of pure Fe2O3-TiO2-Au composites, with gold present only in its metallic state and each of the constituents maintaining its chemical identity.
Samarium electrodeposited acetate and oxide thin films on stainless steel substrate characterized by XPS23(2016); http://dx.doi.org/10.1116/1.4954390View Description Hide Description
Characterization of a samarium thin film deposited on a stainless steel substrate using electrodeposition was carried out with a Thermo Scientific K-Alpha X-ray photoelectron spectrometer. Two types of samarium electrodeposition samples were studied, one as-deposited and one heated to 700 °C in an air atmosphere. Survey scans include peaks coming from the stainless steel substrate, such as Fe and Cr. An x-ray photoelectron spectroscopy (XPS) survey spectrum, Sm 3d, C 1s, and O 1s narrow scans are shown. It was determined, using XPS, that the heating process decomposed the deposited Sm acetate to Sm2O3.