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21.
Danilo Di Genova Daniele Morgavi Kai‐Uwe Hess Daniel R. Neuville Nikita Borovkov Diego Perugini Donald B. Dingwell 《Journal of Raman spectroscopy : JRS》2015,46(12):1235-1244
The effect of chemical composition on the Raman spectra of a series of natural calcalkaline silicate glasses has been quantified by performing electron microprobe analyses and obtaining Raman spectra on glassy filaments (~450 µm) derived from a magma mingling experiment. The results provide a robust compositionally‐dependent database for the Raman spectra of natural silicate glasses along the calcalkaline series. An empirical model based on both the acquired Raman spectra and an ideal mixing equation between calcalkaline basaltic and rhyolitic end‐members is constructed enabling the estimation of the chemical composition and degree of polymerization of silicate glasses using Raman spectra. The model is relatively insensitive to acquisition conditions and has been validated using the MPI‐DING geochemical standard glasses 1 as well as further samples. The methods and model developed here offer several advantages compared with other analytical and spectroscopic methods such as infrared spectroscopy, X‐ray fluorescence spectroscopy, electron and ion microprobe analyses, inasmuch as Raman spectroscopy can be performed with a high spatial resolution (1 µm2) without the need for any sample preparation as a nondestructive technique. This study represents an advance in efforts to provide the first database of Raman spectra for natural silicate glasses and yields a new approach for the treatment of Raman spectra, which allows us to extract approximate information about the chemical composition of natural silicate glasses using Raman spectroscopy. We anticipate its application in handheld in situ terrestrial field studies of silicate glasses under extreme conditions (e.g. extraterrestrial and submarine environments). © 2015 The Authors Journal of Raman Spectroscopy Published by John Wiley & Sons Ltd 相似文献
22.
Lucas Ueberricke Dr. Bahiru Punja Benke Tobias Kirschbaum Dr. Sebastian Hahn Dr. Frank Rominger Prof. Dr. Uwe H. F. Bunz Prof. Dr. Michael Mastalerz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(6):2043-2049
A six-step synthesis towards a tribenzotriquinacene (TBTQ) bearing three quinoxalinophenanthrophenazine (QPP) units is presented. The optoelectronic properties are investigated and the effect of the three-dimensional arrangement of the individual QPP planes is examined using optical spectroscopy, electrochemical analysis and quantum-chemical calculations. 相似文献
23.
Yan Guan Dayu Zhou Jin Xu Xiaohua Liu Fei Cao Xianlin Dong Johannes Müller Tony Schenk Uwe Schroeder 《固体物理学:研究快报》2015,9(10):589-593
A wealth of studies have confirmed that the low‐field hysteresis behaviour of ferroelectric bulk ceramics and thin films can be described using Rayleigh relations, and irreversible domain wall motion across the array of pining defects has been commonly accepted as the underlying micro‐mechanism. Recently, HfO2 thin films incorporated with various dopants were reported to show pronounced ferroelectricity, however, their microscopic domain structure remains unclear till now. In this work, the effects of the applied electric field amplitude, frequency and temperature on the sub‐coercive polarization reversal properties were investigated for 10 nm thick Si‐doped HfO2 thin films. The applicability of the Rayleigh law to ultra‐thin ferroelectric films was first confirmed, indicating the existence of a multi‐domain structure. Since the grain size is about 20–30 nm, a direct observation of domain walls within the grains is rather challenging and this indirect method is a feasible approach to resolve the domain structure. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
24.
Elias C. Rüdiger Michael Porz Manuel Schaffroth Dr. Frank Rominger Prof. Uwe H. F. Bunz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):12725-12728
Two literature‐known TIPS‐ethynyl‐dibromoacenes were prepared and employed to synthesize cyclotrimers by using Yamamoto coupling conditions. Two large, well‐soluble starphenes were isolated in good yields. Crystallographic characterization verifies the triangular shape and shows significant differences in crystal packing. 相似文献
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Hans-Joachim Nees Uwe Bergstrßer Heinrich Heydt Manfred Regitz 《Heteroatom Chemistry》1993,4(5):525-530
The (diazoalkyl)phosphanes 4a–e undergo [4 + 1]-cycloaddition reactions with the tetrahalo-orthobenzoquinones 5a,b to furnish the previously unknown (diazoalkyl)phosphoranes 6a–h . The structure of product 6h has been investigated by X-ray crystallography. 相似文献
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3,5-Bis(2-hydroxyphenyl)-1H-1,2,4-triazole (H2La) and 4-[3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazol-1-yl]benzoic acid (H3Lb) have been prepared, and crystal structure of the intermediate 2-(2-hydroxyphenyl)-4H-1,3-benzoxazin-4-one has been determined. Temperature dependent 1H NMR spectroscopic measurements of H2La indicated dynamic behavior with the equilibrium between the two asymmetric tautomers. For H3Lb, pD-dependent 1H NMR spectroscopic measurements showed small but characteristic shifts in the range of 0 ≤ pD ≤ 1, indicative of a triazole
nitrogen atom protonation; the corresponding pK
a of 0.98 ± 0.04 was determined by spectrophotometric titrations. (H2O, 26°C, 1 M KCl/HCl). Formation of [FeIII(La)]+ (pH 2.5) and [FeIII(La)2]− (pH > 6) was verified by UV-Vis spectroscopy. Complex formation of H3Lb with Al3+ and VO2+ was investigated by 1H NMR spectroscopic titration and cyclic voltammetry, respectively. Single crystals of the phenoxo bridged [VVO(HLb)(EtO)]2·2EtOH were characterized by X-ray structural analysis.
Dedicated to Professor Milan Melník on the occasion of his 70th birthday 相似文献
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