Optical coherence tomography as a method of quality inspection for printed electronics products

Application of time domain, ultra high resolution optical coherence tomography (UHR-OCT) in printed electronics products’ quality inspection is demonstrated. Presented study was done using experimental UHR-OCT device based on a Kerr-lens mode locked Ti:sapphire femtosecond laser, photonic crystal fibre and modified, free-space Michelson interferometer. Possibilities of the technique are demonstrated by analysis of an RF antenna—example of printed electronics products. Measurements were done with submicron axial resolution, offered by UHR-OCT system developed in our laboratory. Such high resolution is necessary due to the thickness of material layers used in printed electronics. In addition to tomography imaging, numerical results were compared with data provided by two commercially available measurement devices: Wyko NT3300 optical profiler and Dektak 8 stylus profiler (both Veeco). Comparison of profile heights and their spatial correlation is presented. Ability for full volumetric reconstruction and accuracy justified with reference measurements prove OCT to be a reliable tool in printed electronics product testing.     

Suzuki coupling catalyzed by chloro({2-[mesityl(quinolin-8-yl-κN)boryl]-3,5-dimethylphenyl}methyl-κC)palladium(II)

The title compound was evaluated as catalyst for Suzuki coupling of aryl halides (X?=?I, Br) with phenylboronic acid at room temperature. The rates of the reactions increase with increasing Hammet sigma constant of m-substituents on the arylhalide. The presence of ortho groups on the arylhalides had the effect of lowering the reaction rates. Density functional theory study of the mechanism for the formation of a Pd⁽⁰⁾ complex from the title molecule was performed. Reductive elimination of chloride and the η⁴-BCCC moiety was endergonic and ruled out as a likely pathway. Instead, conversion of the title molecule to phenyl({2-[mesityl(quinolin-8-yl-κN)boryl]-3,5-dimethylphenyl}methyl-κC)palladium(II) complex is thermodynamically favored and predicted to further react with the solvent and the Suzuki coupling reagents to undergo reductive elimination of diphenyl to form a reactive Pd⁽⁰⁾ complex.     

Local rings of exchange rings

We characterize the exchange property for non-unital rings in terms of their local rings at elements,and we use this characterization to show that the exchange property is Morita invariant for idempotent rings.We also prove that every ring contains a greatest exchange idela(with respect to the inclusion).     

A simple kinetic method for the determination of the reaction model from non-isothermal experiments

In a recent article, we obtained an approximate solution for the evolution of a transformed fraction under isochronal conditions for a large variety of single-step transformations. We verified that this solution is accurate and can, in many instances, be used instead of the exact numerical solutions of the corresponding differential equations. In this article we want to examine the possibilities offered by an analytical solution in the analysis of thermoanalytical curves. We will show that for single-step transformations, our model predicts that under the proper time scaling the thermograms obtained at different heating rates merge into a single curve. This ‘universal curve’ is exclusively related to the kinetic model. In addition, the universal curve can be obtained from experimental thermograms by means of a simple transformation. In this way, the dependence of the experimental curves on the rate constant and the kinetic model can easily be separated, making it possible to independently determine the kinetic parameters and the kinetic model. In addition, one can easily check the validity of the kinetic analysis as well as calculate a reliable statistical measure of the goodness of the single-step assumption.     

Separation of different ion structures in atmospheric pressure photoionization-ion mobility spectrometry-mass spectrometry (APPI-IMS-MS)

This study demonstrates how positive ion atmospheric pressure photoionization-ion mobility spectrometry-mass spectrometry (APPI-IMS-MS) can be used to produce different ionic forms of an analy te and how these can be separated. When hexane:toluene (9:1) is used as a solvent, 2,6-di-tert-butylpyridine (2,6-DtBPyr) and 2,6-di-tert-4-methylpyridine (2,6-DtB-4-MPyr) efficiently produce radical cations [M]⁺ and protonated [M + H]⁺ molecules, whereas, when the sample solvent is hexane, protonated molecules are mainly formed. Interestingly, radical cations drift slower in the drift tube than the protonated molecules. It was observed that an oxygen adduct ion, [M + O₂]⁺, which was clearly seen in the mass spectra for hexane:toluene (9:1) solutions, shares the same mobility with radical cations, [M]⁺. Therefore, the observed mobility order is most likely explained by oxygen adduct formation, i.e., the radical cation forrning a heavier adduct. For pyridine and 2-tert-butylpyridine, only protonated molecules could be efficiently formed in the conditions used. For 1- and 2-naphthol it was observed that in hexane the protonated molecule typically had a higher intensity than the radical cation, whereas in hexane:toluene (9:1) the radical cation [M]⁺ typically had a higher intensity than the protonated molecule [M + H]⁺. Interestingly, the latter drifts slower than the radical cation [M]⁺, which is the opposite of the drift pattern seen for 2,6-DtBPyr and 2,6-DtB-4-MPyr.     

Quantifying the symmetry content of the electronic structure of molecules: molecular orbitals and the wave function

A scheme to quantify the symmetry content of the electronic wave function and molecular orbitals for arbitrary molecules is developed within the formalism of Continuous Symmetry Measures (CSMs). After defining the symmetry operation expectation values (SOEVs) as the key quantity to gauge the symmetry content of molecular wavefunctions, we present the working equations to be implemented in order to carry out real calculations using standard quantum chemistry software. The potentialities of a symmetry analysis using this new method are shown by means of some illustrative examples such as the changes induced in the molecular orbitals of a diatomic molecule by an electronegativity perturbation, the breaking of orbital symmetry along the dissociation path of the H(2) molecule, the changes in the molecular orbitals upon a geometrical distortion of the benzene molecule, and the inversion symmetry content in the different spin states of the [Fe(CH(3))(4)](2-) complex.