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1.
Secondary ion mass spectrometry (SIMS) depth profiling has been applied to the study of the thermal annealing of ohmic contacts
for high electron mobility transistors. The metallic stacks (Ti/Al/Ni/Au) were deposited over the Al0.28Ga0.72N/GaN/sapphire heterostructures and subjected to a rapid thermal annealing (850 °C for 30 s under N2 atmosphere) to improve the contact performance. The surface morphology and the in-depth chemical distribution of the layered
contacts were severely modified due to the treatment. These modifications have been analyzed by SIMS depth profiling and scanning
electron microscopy–energy-dispersive X-ray microanalysis. The SIMS analysis conditions have been optimized to achieve simultaneously
good sensitivity and to avoid ion-induced mixing effects produced by the primary beam sputtering. 相似文献
2.
Dr. Jennifer L. Hickey Prof. Dr. Leonard G. Luyt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(41):12999-13007
Molecular scaffolds have been shown to facilitate and stabilise secondary structural turn elements, with a central core‐arranging functionality in a defined three‐dimensional orientation. In a peptide‐based molecular imaging probe, this approach is of particular value as it would essentially “hide” a metal radioisotope within the ligand framework, making the labelling element a critical component of the receptor‐bound structure. Starting from a 1,2‐diaminoethane loaded 2‐chlorotrityl resin, a versatile set of triamine ligand systems were synthesised by using solid‐phase Fmoc‐based peptide chemistry. The resultant resin‐bound peptides then underwent amide reduction by treatment with borane‐THF at 65 °C. This provided complete conversion to the corresponding polyamine entities in high purity for the majority of the amino acids utilised. The triamines were then coordinated on solid support by using [NEt4]2[Re(CO)3(Br)3] followed by resin cleavage and HPLC purification, to give the desired rhenium coordinated species. We have shown that amino acid sequences can be assembled, reduced and coordinated on‐resin, resulting in a versatile set of metal–ligand constructs. These studies could be expanded to generate libraries of turn‐based peptidomimetics containing Re/TcI organometallic scaffolds, with the intention of developing an improved approach for finding new diagnostic and therapeutic radiopharmaceutical entities. 相似文献
3.
E. Diemann 《无机化学与普通化学杂志》1977,431(1):273-283
Radial Distribution Functions. IV. The Structure of the Non-crystalline Phases Re2S7 and Re2Se7 Using experimental intensities from the powder patterns a radial distribution analysis for the amorphous compounds Re2S7 and Re2Se7 has been made. The interpretation of the experimental distribution curve in terms of pair distribution functions revealed that in rhenium heptasulfide and heptaselenide the same short range order is present which means, that both compounds are isostructural. The shortest rhnium-chalcogen bonds with d(ReS) = 2.38(5) Å and d(ReSe) = 2.47(5) Å do not contain π-contributions. Both substances exhibit stronger Re? Re interactions in the range from 2.6 to 2.9 Å and the metals substructure is quite similar to that of the corresponding dichalcogenides. 相似文献
4.
The investigation of the distribution of trace elements in two chromium samples with different corrosion resistivity is reported. The concentration of the trace elements in both samples is in the typical range of high purity chromium and did not explain the different behaviour in the corrosion test. To measure the three-dimensional distribution imaging secondary ion mass spectrometry (SIMS) was used. Fine details were measured by scanning SIMS because of the better resolution. An enrichment of nitrogen and carbon at the grain boundaries of the sample with lower corrosion resistivity was observed. 相似文献
5.
Riko Ozao Hiroshi Ogura Moyuru Ochiai Sadao Tsutsumi 《Journal of Thermal Analysis and Calorimetry》1997,49(2):961-970
How a DSC result is influenced by the particle size distribution of a powder sample is shown, and a simple and optimal method to be included in a routine DSC analysis (e.g., purity determination) to improve the reliability of the analysis is proposed. In case of-Al2O3 powder, most reliable heat capacity data can be obtained by preparing a powder with a self-similar particle size distribution with a distribution constant of 0.7, and by compressing it under a pressure of 1.5 MPa for a duration of 5 min or longer.This work is partially supported by the Research Fund of North Shore College of SONY Institute. R.O. wishes to express her gratitude to the support. 相似文献
6.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(9):749-753
The CdII three‐dimensional coordination poly[[[μ4‐1,4‐bis(1,2,4‐triazol‐1‐yl)but‐2‐ene]bis(μ3‐5‐carboxybenzene‐1,3‐dicarboxylato)dicadmium(II)] dihydrate], {[Cd2(C9H4O6)2(C8H10N6)]·2H2O}n , (I), has been synthesized by the hydrothermal reaction of Cd(NO3)2·4H2O, benzene‐1,3,5‐tricarboxylic acid (1,3,5‐H3BTC) and 1,4‐bis(1,2,4‐triazol‐1‐yl)but‐2‐ene (1,4‐btbe). The IR spectrum suggests the presence of protonated carboxylic acid, deprotonated carboxylate and triazolyl groups. The purity of the bulk sample was confirmed by elemental analysis and X‐ray powder diffraction. Single‐crystal X‐ray diffraction analysis reveals that the CdII ions adopt a five‐coordinated distorted trigonal–bipyramidal geometry, coordinated by three O atoms from three different 1,3,5‐HBTC2− ligands and two N atoms from two different 1,4‐btbe ligands; the latter are situated on centres of inversion. The CdII centres are bridged by 1,3,5‐HBTC2− and 1,4‐btbe ligands into an overall three‐dimensional framework. When the CdII centres and the tetradentate 1,4‐btbe ligands are regarded as nodes, the three‐dimensional topology can be simplified as a binodal 4,6‐connected network. Thermogravimetric analysis confirms the presence of lattice water in (I). Photoluminescence studies imply that the emission of (I) may be ascribed to intraligand fluorescence. 相似文献
7.
T. Kolber K. Piplits R. Haubner H. Hutter 《Fresenius' Journal of Analytical Chemistry》1999,365(8):636-641
Polycrystalline diamond films have been produced on pre-treated silicon substrate by CVD hot filament method, with B(C2H5)3 added to the gas phase. However, under identical surface conditions, boron incorporation is not homogeneous. In {111} growth sectors, the boron concentration is found to be about 5 times higher than in {100} growth sectors. Moreover, a marked increase in contaminating elements such as aluminium and sodium in regions with higher boron concentrations is detected. Under SIMS fine focus conditions it can be shown that the interface between these two different facet regions is smaller than 0.5 μm. With 3D-depth profile images it can also be shown that the carbon distribution in the diamond layer is not totally homogeneous. 相似文献
8.
T. Kolber K. Piplits R. Haubner H. Hutter 《Analytical and bioanalytical chemistry》1999,365(8):636-641
Polycrystalline diamond films have been produced on pre-treated silicon substrate by CVD hot filament method, with B(C2H5)3 added to the gas phase. However, under identical surface conditions, boron incorporation is not homogeneous. In {111} growth sectors, the boron concentration is found to be about 5 times higher than in {100} growth sectors. Moreover, a marked increase in contaminating elements such as aluminium and sodium in regions with higher boron concentrations is detected. Under SIMS fine focus conditions it can be shown that the interface between these two different facet regions is smaller than 0.5?μm. With 3D-depth profile images it can also be shown that the carbon distribution in the diamond layer is not totally homogeneous. 相似文献
9.
A unique 3‐D PbII coordination polymer containing ligands 1,2‐bis(4‐pyridyl)ethylene (bpe) and 3‐sulfobenzoate (3‐sb), [Pb(3‐sb)(bpe)0.5]n ( 1 ) has been synthesized by hydrothermal reaction and characterized by elemental analysis, IR, TGA, 1H NMR, powder X‐ray analysis, and fluorescent spectrum. The single‐crystal X‐ray analysis shows that eight coordination bonds can be divided as five primary bonds and three secondary bonds. The secondary bonds largely enhance the solid stability and provide a high‐dimensional network assembly. The complex also displays strong fluorescent property. 相似文献
10.
Pure perovskite lead titanate powder (PbTiO3) is successfully produced via the sol–gel process using lead and titanium glycolates as starting precursors and has been synthesized by the oxide one spot synthesis process. The obtained lead titanate is of the tetragonal form of the perovskite phase, with high purity and nearly zero moisture content. From high‐resolution mass spectra, the XRD technique, Raman‐FTIR and TGA‐DTA analysis, the lead–titanium glycolates undergo sol–gel transition through the formation of Pb? O? Ti bonds. From the SEM micrographs, the PbTiO3 particle shape transforms from an agglomerate sphere to a needle and fiber‐like shapes as the calcination temperature is varied above Tc. The corresponding molecular structural transformation, from the tetragonal form to the cubic form, occurs at 430 °C. The lead titanate powder calcined at 300 °C for 3 h has the highest dielectric constant and electrical conductivity values, namely 17470 and 1.83 × 10?3, respectively. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
11.
Hydroxylation of the silica in microfabricated thin layer chromatography plates as probed by time‐of‐flight secondary ion mass spectrometry and diffuse reflectance infrared Fourier transform spectroscopy
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Supriya S. Kanyal Bhupinder Singh Cody V. Cushman Daniel T. Jankowski Matthew R. Linford 《Surface and interface analysis : SIA》2015,47(3):340-344
Microfabricated silica thin layer chromatography (TLC) plates have previously been prepared on patterned carbon nanotube forests. The high temperatures used in their fabrication reduce the number of hydroxyl groups on their surfaces. Fortunately, silica can be rehydroxylated. In diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), a silanol peak below 3740 cm?1 indicates a well‐hydroxylated silica surface that is fit for chromatography. Hydroxylations of our materials with HF are so effective that it is not possible to discern the position of this peak. In contrast, this signal is discernable when the plates are treated with NH4OH. To find a more convenient method for studying the surfaces of TLC plates, time‐of‐flight secondary ion mass spectroscopy (ToF‐SIMS) was considered. ToF‐SIMS is advantageous because multiple microfabricated TLC plates must be scraped to obtain enough silica for one DRIFT analysis, while static SIMS can be performed on very small regions (500 × 500 µm2 or less) of individual plates. Ratios of the SiOH+ and Si+ ToF‐SIMS signals for microfabricated TLC plates correlated well with ~3740 cm?1 silanol peaks from DRIFT. Thus, SIMS allows direct analysis of all of our treated and untreated plates, including those hydroxylated with HF. The best hydroxylation condition for HF, which was better than any studied for NH4OH, was around 150 ppm at room temperature. The best hydroxylation condition for NH4OH was 50 °C for 72 h. ToF‐SIMS versus DRIFT results of commercial TLC plates were also obtained and evaluated. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
12.
Benign‐by‐Design Solventless Mechanochemical Synthesis of Three‐, Two‐, and One‐Dimensional Hybrid Perovskites
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Alexander D. Jodlowski Dr. Alfonso Yépez Prof. Rafael Luque Prof. Luis Camacho Prof. Gustavo de Miguel 《Angewandte Chemie (International ed. in English)》2016,55(48):14972-14977
Organic–inorganic hybrid perovskites have attracted significant attention owing to their extraordinary optoelectronic properties with applications in the fields of solar energy, lighting, photodetectors, and lasers. The rational design of these hybrid materials is a key factor in the optimization of their performance in perovskite‐based devices. Herein, a mechanochemical approach is proposed as a highly efficient, simple, and reproducible method for the preparation of four types of hybrid perovskites, which were obtained in large amounts as polycrystalline powders with high purity and excellent optoelectronics properties. Two archetypal three‐dimensional (3D) perovskites (MAPbI3 and FAPbI3) were synthesized, together with a bidimensional (2D) perovskite (Gua2PbI4) and a “double‐chain” one‐dimensional (1D) perovskite (GuaPbI3), whose structure was elucidated by X‐ray diffraction. 相似文献
13.
Ryuji Hirase Koji Honda Mari Ishihara Hideki Yoshioka Hirosato Monobe 《Tetrahedron letters》2018,59(5):469-472
We have investigated synthesis as well as purification of 5,5?-bis(tridecafluorohexyl)-2,2′:5′,2″:5″,2?-quaterthiophene (BFH-4?T, n-type organic semiconducting material) using supercritical carbon dioxide (scCO2) as a green solvent. BFH-4T was obtained in good selectivity and high yield by TDAE/PdCl2-catalyzed reductive coupling reaction of 5-bromo-5′-(tridecafluorohexyl)-2,2′-bithiophene in scCO2. We have also successfully established purification of the reaction mixture by passing scCO2 in the reaction vessel. The product was yellow powder of BFH-4T with purity of more than 99% and Pd catalyst was not contained. 相似文献
14.
Donna J. Nelson Christopher N. Brammer 《Analytical and bioanalytical chemistry》2010,396(3):1079-1086
Proper purity characterization of single-walled carbon nanotubes (SWCNTs) is an increasingly hot topic in the area of carbon
nanotechnology. There are inconsistencies in purity characterization of SWCNT from manufacturers and in the literature. Purity
of “as received,” oven dried, and NaHCO3-washed SWCNTs of three commercially available brands (NanoLab, SWeNT, and HiPco) is explored by using a consistent methodology
via proton nuclear magnetic resonance (1H NMR) spectroscopy comparison, across three NMR solvents: DMSO-d
6, CDCl3, and D2O. Important insights into the purity of commercially available SWCNT and the importance of washing (cleaning) samples before
use are offered. 相似文献
15.
This work presents the benefits of coupling techniques such as Electro Thermal Vaporisation (ETV)-ICP-MS and Ion Chromatography (IC)-ICP-(AES, MS) for ultra trace analysis in a high purity rhenium powder sample. Direct analysis using ICP-AES suffers from poor detection limits and allows trace analysis only above 1 g/g for most analytes. ICP-MS analysis of trace elements is more sensitive, but signal depression caused by the heavy Re-ions limits trace analysis to concentrations of 50–100 ng/g analyte in the solid sample. Coupling Ion Chromatography with ICP-spectrometers, combined with time resolved measurement (IC-ICP-TRM) of the elution signals, was used to enhance the sensitivity of both ICP-AES and ICP-MS. Resulting detection limits are in the very low ng/g to pg/g range. Coupling of ETV and ICP-MS offers the possibility of eliminating the volatile Re2O7 matrix by thermal pretreatment and allows ICP-MS measurements without matrix interferences caused by Re. Results from these methods are compared with Glow Discharge Mass Spectrometry (GDMS) analysis, a semiquantitative solid state technique. The results are also compared with the manufacturers' specifications to show the power of modern routine analysis using ICP-AES or FAAS. 相似文献
16.
Summary Dynamic secondary ion mass spectrometry (DSIMS) investigations have been carried out with Cr, Mn, Fe, Co, Mo, Rh, W, Re, Os and Ir under 4 mPa N2O, NO and 3 mPa NO2 as reactant gases. Results indicate similar behaviour in adsorption for Cr, Mn, Fe, Mo, W on the one hand and for Co, Rh, Os and Ir on the other. For the first group of metals the nitrogen oxide molecules are always totally destroyed in adsorption whereas the second group shows evidence for surface compounds such as MeNO (Me=metal) indicating only a partial dissociation in the case of N2O and NO2, and molecular adsorption under NO respectively. Re does not belong uniquely to either group because it reacts with N2O and NO2 dissociatively whereas under NO only partial dissociation is observed.Abbreviations SIMS
Secondary ion mass spectrometry
- SSIMS
Static SIMS
- AES
Auger electron spectroscopy
- EELS
Electron energy-loss spectroscopy
- LEED
Low energy electron diffraction
- TDS
Thermal desorption spectroscopy
- XPS, UPS
X-ray/Ultraviolet photoelectron spectroscopy 相似文献
17.
Jiaoyun Xia Yongxian Wang Junfeng Yu Jinquan Cao Chunfu Zhang Duanzhi Yin 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(2):313-316
Summary Fac-[188Re(CO)3(H2O)3]+ was synthesized with an overall radiochemical yield of 80±5%, and more than 95% radiochemical purity after a QMA Sep-Pak
column separation. Fac-[Re(CO)3(H2O)3]+ was also synthesized as a reference sample. The structure of the precursor, fac-[188Re(CO)3(H2O)3]+, was confirmed by high performance of liquid chromatography (HPLC). MN-His (magnetic nanoparticles coated with silica and
modified with an amino silane coupling agent, N-[3-(trimethyoxysilyl)propyl]-ethylenediamine (SG-Si900) and immobilized with
histidine) was labeled with fac-[188Re(CO)3(H2O)3]+ and an initial animal test of MN-His was conducted for a magnetic targeting study. 相似文献
18.
Xiao‐Dan Wang Guang‐Feng Hou Ying‐Hui Yu Jin‐Sheng Gao 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(12):m336-m339
The title compound, {[Ni(C9H4O6)(C14H14N4)]·0.41H2O}n, exhibits a three‐dimensional hydrogen‐bonded supramolecular framework. The NiII cation is six‐coordinated in a distorted triangular prism defined by two N atoms from two 1,3‐bis(imidazol‐l‐ylmethyl)benzene (bix) ligands and four O atoms from two 5‐carboxybenzene‐1,3‐dicarboxylate (HBTC) dianions. The bix molecules and HBTC dianions both act as bidentate ligands, linking the NiII cations to form a one‐dimensional coordination polymer. A two‐dimensional wave‐like net is constructed by O—H...O hydrogen bonds linking adjacent chains. Partially occupied solvent water molecules fill the cavities and link these layers to form a three‐dimensional supramolecular structure via O—H...O hydrogen bonds. The title compound was also characterized by powder X‐ray diffraction and thermogravimetric analysis. 相似文献
19.
A three‐dimensional (3D) manganese (II) coordination polymer: Synthesis,structure and catalytic activities
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A new Mn (II)‐containing coordination polymer, [Mn6(Ipa)6(ad)?6H2O] ( 1 ; Ipa = isophthalate ligand; ad = adenine), was synthesized by reacting hydrated manganese nitrate with isophthalic acid and adenine under solvothermal reaction conditions. Polymer 1 was characterized using single‐crystal X‐ray diffraction analysis and other techniques such as Fourier transform infrared spectroscopy, elemental analyses and powder X‐ray diffraction. The solid‐state structure of 1 confirmed the formation of a three‐dimensional framework structure based on Mn6 secondary building units. Phase purity of bulk 1 and its thermal stability were investigated. Polymer 1 was evaluated for its performance as a heterogeneous catalyst for the Henry (nitroaldol) reaction of nitromethane with several aldehydes. The recyclability of 1 and heterogeneity of the reaction were also explored. A plausible mechanism for such reaction is proposed. To the best of our knowledge, polymer 1 represents the first example of a Mn (II)‐ and adenine‐containing coordination polymer as well as the first example of a Mn (II)‐containing coordination polymer that has been employed for the Henry reaction. 相似文献
20.
Secondary ion mass spectrometry (SIMS) was optimised for characterisation of uranium- and plutonium-containing particles
in soils, swipes and forensic samples. This was done by analysing in-house produced spherical UO2-particles. Screening techniques as α-autoradiography together with SIMS analysis were employed to detect UO2-particles in a soil sample from Chernobyl.
The use of SIMS was exploited for the identification of uranium- and plutonium-containing particles and for the determination
of their isotopic composition. The particles collected on swipe samples were transferred to a special adhesive support for
the analysis by SIMS. Particles containing highly enriched uranium with diameters up to 10 μm were also detected in a forensic
sample. For the measurements of the isotopic ratios a mass resolution of 1000 was used. At this resolution flat-top peaks
were obtained which greatly improve the accuracy of the measurement. The isotopic composition of the particles was measured
with a typical accuracy and precision of 0.5%. Statistically meaningful results can be obtained, for instance, from a specimen
containing as few as 1010 atoms/μm3 of uranium in particles of UO2 weighing a few picograms. 相似文献