Optimizing the sputter deposition process of polymers for the Storing Matter technique using PMMA

Quantitative analyses in secondary ion mass spectrometry (SIMS) become possible only if ionization processes are controlled. The Storing Matter technique has been developed to circumvent this so‐called matrix effect, primarily for inorganic samples, but has also been extended to organic samples. For the latter, it has been applied to polystyrene in order to investigate the extent of damage in the polymer, its fragmentation during the sputter deposition process and the effect of the deposition process on the spectra taken by Time‐of‐Flight SIMS (ToF‐SIMS). In this work, a multi‐technique approach, which employs the Storing Matter technique for deposition and ToF‐SIMS and X‐ray photoelectron spectroscopy for characterization, is used to enhance the control of the deposition process, including the thickness of the deposit, the alteration of the source film and the influence of polymer composition on the Storing Matter process. Poly (methyl methacrylate) (PMMA) is used for this work. More detailed information about the sticking of polymer fragments on the metal collector is obtained by density functional theory calculations. This work allows for the conclusion that a part of the fragments deposited on the collector surface diffuses on the latter, reacts and recombines to form larger fragments. The behaviour observed for PMMA is similar to polystyrene, showing that oxygen has no major influence on the processes occurring during the sputter deposition process. Additionally, we have developed a new methodology using 2D ToF‐SIMS images of the deposit to monitor the deposit thickness and to identify surface contaminations. The latter are not only located at the position of the deposit but all over the collector surface. Copyright © 2016 John Wiley & Sons, Ltd.     

Investigation of structural and optical properties of ZnO films co-doped with fluorine and indium

Undoped ZnO film and ZnO films, which are co-doped with F and In (FIZO) at different concentrations, were synthesized by sol–gel technique and the effects of co-doping of F and In on structural and optical properties of ZnO thin films were investigated. The concentration ratio of [F]/[Zn] was altered from 0.25 to 1.75 with 0.50 step at.% mole and [In]/[Zn] was altered from 0.25 to 1.00 with 0.25 step at.% mole. X-ray diffraction analysis indicates that the films have polycrystalline nature and the (0 0 2) preferred orientation is the stronger peak. No extra phases involving zinc, fluorine and indium compounds were observed even at high F and In content. The grain size of undoped ZnO and FIZO thin films varied between 15 and 20 nm with a small fluctuation. From the SEM images, although the undoped ZnO had a smooth and particle-shaped surface, FIZO films had nanofiber-networks shapes over the surface with average size of 500 nm. The surface morphologies and crystallite sizes for the F and In doped films were slightly different from than those of undoped film. From the optical study, a slight shrinkage of band gap was backwardly observed from 3.36 to 3.25 eV with the increasing of F and In content.     

Three-dimensional flow structure on a maneuvering wing

Unsteady plunging (heaving) of a wing in the form of a flat plate can give rise to pronounced axial flow in the small-scale leading-edge vortex, during its initial stage of formation. Opposing axial flows along the vortex interact at the plane of symmetry giving rise to large-scale patterns of streamwise-oriented vorticity, which can dominate the tip vortices over part of the oscillation cycle.     

2‐[(4‐Hydroxyphenyl)iminomethyl]­thiophene

The molecular structure of the title compound, C₁₁H₉NOS, has three planar moieties, two of which are rings, namely the hydroxy­phenyl and the thio­phene, with an angle of 20.76 (10)° between them. The crystal structure is stabilized by an O—H?N hydrogen bond and by C—H?O intermolecular interactions. The C?O intermolecular contact distance is 3.443 (2) Å.     

A polydentate ligand based on 2,2’-dipyridylamine unit linked benzo-15-crown-5; alkali and transition metal complexes; photoresponsive ligand; antimicrobial evaluation against pathogenic microorganisms

Transition Metal Chemistry - New double-armed benzo-15-crown-5 compound (L) was successfully synthesized from 4’,5’-bis(bromethyl)benzo-15-crown-5 with 2,2’-dipyridylamine. The...     

Contemporary Photoligation Chemistry: The Visible Light Challenge

Catalyst-free and bond-forming light-induced reactions have seen an unprecedented renaissance in the realm of soft matter materials science due to their efficiency, spatio-temporal controllability and, sometimes, photoreversible nature. However, many of these reactions rely on the application of high energy UV light that can cause photo-degradation and is inapplicable in biological environments. If up-conversion systems or two-photon processes are to be avoided, strategies for red-shifting catalyst-free ligation technology are critically required. This Concept article introduces the reader to recent methods that lead to efficient, catalyst-free visible-light-induced ligation chemistry based on polyaromatic substituted photoreactive compounds—pyrene and anthracene—and, furthermore, emphasizes the broad and facile applicability of these molecules in polymeric material design. Concomitantly, we highlight that a careful action plot analysis of photochemical reactivity can provide deep insights into reactivity patterns, far beyond those suggested by the absorption spectrum. Indeed, we suggest that an action plot analysis is necessary for the evaluation of any photochemical system and its response to structural chemical changes.     

Fibonacci oscillators

We discuss the properties of oscillators whose spectrum is given by a generalized Fibonacci sequence. The properties include: invariance under the unitary quantum group, generalized angular momentum, coherent states and difference calculus, relativistic interpretation.     

Determination of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in food and beverages

The determination of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) in food and beverages sold in Turkey was carried out using liquid chromatography–tandem mass spectrometry (LC-MS/MS). A total of 123 samples of selected food and beverages such as fish, meat, offal, egg, cracker, chips, cake, chocolate, vegetable, milk and juice were examined. The highest PFOA concentrations were determined in cow meat (5.15 ng g^?1), cow kidney (5.65 ng g^?1), cow spleen (5.06 ng g^?1) and chicken liver (5.02 ng g^?1). The highest PFOS levels were found in horse mackerel (52.43 ng g^?1), pike-perch (45.87 ng g^?1), sardine (42.83 ng g^?1) and black cod (41.33 ng g^?1). Fish was found to be major source of the PFOS intake, while meat and offal were found to be major sources of the PFOA intake.     

Determination of total attenuation cross sections of Ti, Fe, Ni, Zn between 4.551–111.898 keV energy range

The total attenuation cross sections in elements Ti, Fe, Ni and Zn for K and K group of liens of element 22Z92 by using tranmission method. K X-rays of seconder excitor were counted by a Ge(Li) detector with resolution 190 eV at 5.9 keV. The experimentally mesured attentuation cross sections have ben found in a good agreement with the theoretical values of Stom, Israel and Hubbell, Seltzer.     

Direct determination of total atomic attenuation,total atomic photoelectric and total atomic scattering cross sections of Gd,Tb, Dy and Er at 60 keV

A simple and direct method has been used to obtain fairly accurate total atomic attenuation, total atomic photoelectric and total scattering cross sections by measuring the transmission factor and K X-ray fluorescence spectrum induced by 60 keV -rays for Gd, Tb, Dy and Er by employing a Si(Li) detector system in a 2 geometry set-up. All the parameters are compared with their corresponding theoretical values and a good agreement between them is obtained.