共查询到20条相似文献,搜索用时 31 毫秒
1.
Sabine Dreer Peter Wilhartitz Bernhard Sartory Richard Tessadri Kurt Piplits Karl Emanuel Mayerhofer 《Mikrochimica acta》2006,155(1-2):125-128
Low amounts of oxygen in AlCrN hard coatings have been quantitatively analysed by means of WDS–EPMA. By combination with SIMS
depth profiling, applying a calibration sample produced by ion implantation, the accuracy of the EPMA results was proven.
Values as low as 0.07 at% were measured and the calculated detection limit is in the range of 0.01 at%. 相似文献
2.
Dagmar Dietrich Peter Willich Sabine Stöckel Kathrin Weise Günter Marx 《Mikrochimica acta》2000,133(1-4):183-186
A suitable fibre coating is essential to obtain optimal fibre-matrix interaction in fibre-strengthened composite materials.
Thin films (∼100 nm) of silicon carbide, turbostratic carbon, and boron nitride were deposited by CVD as single or double
layers on commercial multi-filament fibres in a continuous process. The fibre material itself may be carbon, alumina, silicon
carbide, or a quaternary ceramic of SiCBN. The application of MCs+-SIMS enables one to determine the composition (including impurities of H and O) of various fibre coating materials with an
accuracy of at least 20% relative. Due to the special geometry of the multi-filament samples the depth resolution of the SIMS
depth profiles is limited, nevertheless, layered structures and some details of the interface between coating and fibre can
be studied. The depth calibration of the SIMS depth profiles is derived from sputter rates established on flat samples with
a composition similar to that of the fibre coating material. However, the obtained film thicknesses are not extremely different
from the values derived from TEM on cross sections of coated fibres. 相似文献
3.
U. Zastrow R. Loo K. Szot J. Moers T. Grabolla D. Behammer L. Vescan 《Analytical and bioanalytical chemistry》1997,358(1-2):203-207
SIMS depth profiling during O2
+ bombardment has been performed to analyse epitaxially grown Si p-n-p layers, which define the p-channel region in vertical
Si-p MOS transistors, as well as to establish “on-chip” depth profiling of the functional vertical device. The SIMS detection
limit of 31P in Si, phosphorus used as n-type dopant in the transistor, has been optimised as a function of the residual gas pressure
in the SIMS analysis chamber and of the sputter erosion rate. We demonstrate that good vacuum during SIMS analysis combined
with high erosion rates allows the simultaneous quantitative SIMS depth profiling of n- and p-type dopant concentrations in
the vertical transistor. Small area “on-chip” SIMS depth profiling through the layered structure of Al-contact/TiSi2/Si(p-n-p)/Si-substrate has been performed. Factors influencing the depth resolution during “on-chip” analysis of the transistor
are discussed especially in terms of sputtering induced ripple formation at the erosion crater bottom, which has been imaged
with atomic force microscopy.
Received: 15 August 1996 / Revised: 17 January 1997 / Accepted: 21 January 1997 相似文献
4.
U. Breuer H. Holzbrecher M. Gastel J. S. Becker H.-J. Dietze 《Fresenius' Journal of Analytical Chemistry》1995,353(3-4):372-377
For the quantification of heterostructure depth profiles the knowledge of relative sensitivity factors (RSF) and the influence of matrix effects on the measured profiles is necessary. Matrix dependencies of the measured ion intensities have been investigated for sputtered neutral mass spectrometry (SNMS) and MCs+-SIMS. The use of Cs as primary ions for SNMS is advantageous compared to Ar because the depth resolution is improved without changing RSFs determined under Ar bombardment. No significant amount of molecules has been found in the SNMS spectra under Cs bombardment. Using MCs+-SIMS the RSFs are matrix dependent. An improvement of depth resolution can be achieved by biasing the sample against the primary ion beam for SNMS due to a reduction of the net energy of the primary ions and a resulting more gracing impact angle. 相似文献
5.
J. -P. Pfeifer H. Holzbrecher W. J. Quadakkers U. Breuer W. Speier 《Fresenius' Journal of Analytical Chemistry》1993,346(1-3):186-191
Summary Attempts to obtain a quantitative analysis of depth profiles of oxide films on iron-based ODS-alloys using MCs+-SIMS and e-beam SNMS are presented. Since the oxide films of the alloys consist mainly of alumina, implantation standards in Al2O3(sapphire) were used for the quantification of the measured depth profiles. The so-called matrix effect, normally present in SIMS analysis, is strongly reduced by recording the MCs+-secondary ions. Over a wide concentration range, agreement between SIMS and SNMS data is obtained within a factor 2–3. The evaluated concentration profiles for the main alloying elements in combination with 18O tracer-experiments have been used to give an interpretation of the growth processes of the oxide films for Fe-based ODS-alloys, with and without the addition of an yttria dispersion. The results show that the addition of yttria dispersion is responsible for the dramatic change observed in the oxide growth mechanism.ODS=Oxide Dispersion strengthenedThis poster was awarded the First Prize in Poster Session A by the Deutscher Arbeitskreis für Spektroskopie (DASp) 相似文献
6.
Summary The use of Cs+ primary ions in conjunction with the detection of MCs+ molecular ions (where M is the element to be monitored) in SIMS depth profiling is shown to be an efficient method of minimizing the variations of ion yields with sample composition, e.g., at the interface of multilayer structures. Depth profiles of several such samples demonstrate that MCs+ intensities follow closely the concentrations of the respective elements, providing the possibility of a (semi)quantitative analysis of major components by means of secondary ion mass spectrometry. As indicated by the similarity of their energy distribution data, the formation and emission process of MCs+ molecules seems coupled to that of Cs+ ions. 相似文献
7.
A “dust-free” sol-gel microsphere pelletisation (SGMP) process has been developed for fabrication of (U,Pu)O2, (U,Pu)C and (U,Pu)N fuel pellets containing around 15% plutonium for the forthcoming prototype fast breeder reactor (PFBR)
in India. The objective was to produce homogeneous sintered pellets of ∼85% T.D. with a predominantly open-pore structure.
Hydrated gel-microspheres of UO3+PuO2 and UO3+PuO2+C have been prepared from nitrate solutions of uranium and plutonium by the “ammonia internal gelation” process, using hexamethylene
tetramine (HMTA) as an ammonia generator and silicone oil at 90±1°C as gelation bath. For oxide fuel pellets, the hydrated
UO3+PuO2 gel-microspheres were calcined at around 700°C in Ar+8% H2 atmosphere to produce “non-porous”, “free-flowing” and coarse (around 400 micron) microspheres which could be directly pelletised
at 550 MPa to green pellets. The mixed oxide pellets were subjected either to low temperature (∼1100°C) oxidative sintering
(LTS) in N2+air containing ∼1500 ppm O2 or to high temperature (1650°C) sintering, (HTS) in Ar+8% H2. For monocarbide and mononitride pellets, hydrated gel-microspheres of UO3+PuO2+C were subjected to carbothermic synthesis in vacuum (∼1 Pa) and flowing nitrogen (flow rate: 1.2 m3/h) in the temperature range of 1450–1550°C respectively. The monocarbide and mononitride microspheres thus produced were
relatively hard and required higher compaction pressure (∼1200 MPa) for making reen pellets which could be sintered to 85%
T.D. in Ar+8% H2 at 1700°C. The sintered oxide, monocarbide and mononitride pellets had a “blackberry” “open” pore microstructure with fine
grain size. The microspheres retained their individual identity in the sintered pellets because during sintering densification
took place mainly within and not between the microspheres. 相似文献
8.
Hisayoshi Matsushima Adriana Ispas Andreas Bund Waldfried Plieth Yasuhiro Fukunaka 《Journal of Solid State Electrochemistry》2007,11(6):737-743
The electrodeposition process of Co films in a sulfuric acid solution was examined in a magnetic field (0–5 T). The surface
morphology of Co films electrodeposited without a magnetic field was drastically modified with the variation of hydrogen gas
evolution rate. Crystalline α-Co was formed in the range of pH = 1.5–6.0, while β-Co was not observed. When the magnetic field
was superimposed perpendicular to the electric field in the acidic solution (pH = 1.5), the hydrogen evolution rate was promoted
by MHD convection, which enhanced the ionic mass transfer (H+ and Co2+) near the electrode surface. Moreover, crystalline β-Co was formed simultaneously with the appearance of the elongated ridge-shape
precipitates under a higher magnetic field (≥3 T).
Contribution to special issue “Magnetic field effects in Electrochemistry” 相似文献
9.
Asakawa D Moriguchi S Takayama M 《Journal of the American Society for Mass Spectrometry》2012,23(1):108-115
The influence of arginine (Arg), lysine (Lys), and phenylalanine (Phe) residues and phosphorylation on the molecular ion yields
of model peptides have been quantitatively studied using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry
in both positive- and negative-ion mode. The results obtained from these experiments have been interpreted from the standpoint
of two different components, namely, desorption and ionization, on the basis of the physicochemical properties of constituent
amino acids of the model peptides. The presence of basic residues such as Arg and Lys enhanced the ion yields of protonated
molecules [M + H]+. An N-terminal rather than a C-terminal Arg residue was advantageous for the formation of both [M + H]+ and [M – H]–. The presence of the Phe residue resulted in the increase of the ion yields of both [M + H]+ and [M – H]–. In contrast, the presence of phosphate group(s) contributed to the suppression of the yields of both [M + H]+ and [M – H]– due to the loss of phosphate group. The detection limits for both [M + H]+ and [M – H]– of model peptides have been evaluated. 相似文献
10.
Hans Oechsner 《Surface and interface analysis : SIA》2022,54(6):657-660
The formation of MCs+ secondary ions in SIMS operated with Cs+ ion beams is discussed on the basis of a well-confirmed quadratic dependence of MCs+ yields on the atomic polarizabilities of elements M contained in semiconductor samples. This behavior is understood by the generation of a dipole induced in M by the positive charge of a neighboring Cs+ projectile and the mutual induction of a dipole in Cs+, both dipoles depending on the atomic polarizability of M. An evaluation of the dipole–dipole interaction energy indicates that MCs+ ions generated at the target are emitted according to the direct emission model (DEM). This mechanism is in contrast with an association model where constituents of MCs+ are assumed to combine after their independent sputter emission. 相似文献
11.
The emission of MCs+ molecular ions sputtered by Cs+ ion impact from a variety of elemental (Si and Ge) and compound (GaAs, InP, InSb, ZnSe, CdS, CdSe, CdTe and CdZnTe) semiconductors and a selection of glass samples of different composition has been investigated. For the glass samples a set of relative sensitivity factors has been determined which are largely composition-independent and provide the possibility of a reliable quantification of glasses by MCs+ SIMS. For the semiconductors fractional ion yields (i.e. the number of detected MCs+ ions per sputtered M atom) range from 10–6 to some 10–4 and exhibit little variation with the oxygen surface coverage of the specimen. Depending on M, the emission of MOCs+ molecular species becomes prominent (or even dominating) at high oxygen concentrations. Furthermore, total sputtering yields for 5.5 keV Cs+ impact and different oxygen partial pressures have been determined from sputtered craters. 相似文献
12.
We use a multiple-analytical approach based on secondary-ion mass-spectrometry (SIMS), X-ray single-crystal structure refinement
(SREF) and electron-probe micro-analysis (EPMA) to derive the complete crystal-chemical formula of a B-rich kornerupine-group
mineral, prismatine, from Hrarigahy, Madagascar: (Ca0.01Li0.02Mg0.20Fe2+
0.10) (Mg3.57Fe2+
0.06 Al5.37) (Si3.84B0.91Al0.26)O21 (OH1.08F0.07). SIMS matrix effects related to crystal structure were investigated by analyzing two grains with a known crystallographic
orientation relative to the ion beam.
Boron orders at the T3 site. The refined site-scattering for T3, 6.33 eps (electrons per site) agrees well with the mean bond-length for this site (1.512 ?), which indicates nearly complete
occupancy by B (85% rel.). B2O3 (∼ 4 wt%), derived by SREF, agrees with the SIMS data within analytical uncertainty using Si as the inner reference for the
matrix. The occupancy of the X site obtained by combining the SIMS and EPMA data (5.30 eps; electrons per site) agrees with the refined site-scattering
value (5.75 eps). Trace quantities of Li and Ca are ordered at this site. SIMS data for H2O is in accord with the stoichiometric value, indicating complete occupancy at O10 by OH. Fluorine (∼ 0.17 wt%) orders at O10: it corresponds to ∼ 0.07 atoms per formula unit (apfu) vs. 0.15 apfu (atoms per formula unit) by SREF, indicating a slight
overestimation of F with SREF, as previously observed in fluoborite.
Our data show that SIMS chemical matrix effects are well-calibrated, and emphasize the usefulness of independent micro-analytical
techniques in testing the mutual accuracy and consistency of experimental data. 相似文献
13.
Vesuvianite, a complex sorosilicate, often contains variable (from trace-to-minor-element) amounts of H, B and F. We describe
a microanalytical study of H, B and F in vesuvianite by means of Electron Probe Microanalysis (EPMA), Secondary Ion Mass Spectrometry
(SIMS), and single-crystal Fourier-Transform InfraRed (FTIR) spectroscopy. Most crystals investigated are B- (up to 3.67 wt%
B2O3) and F-rich (up to 2.38 wt%); H2O ranges from 0.243 to 0.665 wt%. The H data obtained by SIMS allowed us to calibrate the quantitative analysis of H2O by FTIR spectroscopy. The resulting molar absorption coefficient (ɛ
i
= 100 000 ± 2000 L · mol−1 · cm−2) is in excellent agreement with working curves available from the literature. Moreover, the SIMS data allowed us to obtain
the calibration curve to estimate the B2O3 content on the basis on the FTIR absorbance: a
i
= 34000 ± 1400 · B2O3 (wt%). 相似文献
14.
The emission of MCs+ molecular ions sputtered by Cs+ ion impact from a variety of elemental (Si and Ge) and compound (GaAs, InP, InSb, ZnSe, CdS, CdSe, CdTe and CdZnTe) semiconductors and a selection of glass samples of different composition has been investigated. For the glass samples a set of relative sensitivity factors has been determined which are largely composition-independent and provide the possibility of a reliable quantification of glasses by MCs+ SIMS. For the semiconductors fractional ion yields (i.e. the number of detected MCs+ ions per sputtered M atom) range from 10?6 to some 10?4 and exhibit little variation with the oxygen surface coverage of the specimen. Depending on M, the emission of MOCs+ molecular species becomes prominent (or even dominating) at high oxygen concentrations. Furthermore, total sputtering yields for 5.5 keV Cs+ impact and different oxygen partial pressures have been determined from sputtered craters. 相似文献
15.
Jiménez Zapata I Pohl P Bings NH Broekaert JA 《Analytical and bioanalytical chemistry》2007,388(8):1615-1623
The suitability of a 2.45-GHz atmospheric pressure, low-power microwave microstrip plasma (MSP) operated with Ar and He for
the determination of Hg by continuous-flow cold vapor (CV) generation, using SnCl2/HCl as the reducing agent, and optical emission spectrometry (OES) using a small CCD spectrometer was studied. The areas
of stability for a discharge in the Ar and in the He MSP enclosed in a cylindrical channel in a quartz wafer were investigated.
The excitation temperatures as measured for discharge gas atoms (Ar I, He I), and the electron number densities at 35–40 W
and 15–400 mL min−1 were found to be at the order of 3,200–5,500 K and 0.8 × 1014–1.6 × 1014 cm−3, respectively. The relative intensity of the Hg I 253.6-nm line and the signal-to-background ratio as a function of the forward
power (35–40 W) as well as of the flow rate of the working gas (15–400 mL min−1) were evaluated and discussed. For the selected measurement conditions, the Ar MSP was established to have the lower detection
limit for Hg (0.6 ng mL−1) compared with the He MSP. The linearity range is up to 300 ng mL−1 and the precision is on the order of 1–3%. With the optimized CV Ar MSP-OES method a determination of Hg in spiked domestic
and natural waters at concentration levels of 20–100 μg L−1 and an accuracy of 1–4% could be performed. In an NIST domestic sludge standard reference material, Hg (3.64 μg g−1) could be determined with a relative standard deviation of 4% and an agreement better than 4%. 相似文献
16.
So Hee Yoon Jeong Hee Moon Myung Soo Kim 《Journal of the American Society for Mass Spectrometry》2010,21(11):1876-1883
In-source decay (ISD) and post-source decay (PSD) of a peptide ion ([Y6 + H]+) and a preformed ion (benzyltriphenylphosphonium, BTPP) generated by matrix-assisted laser desorption ionization (MALDI)
were investigated with time-of-flight mass spectrometry. α-Cyano-4-hydroxycinammic acid (CHCA) and 2,5-dihydroxybenzoic acid
(DHB) were used as matrices. For both ions, ISD yield was unaffected by delay time, indicating rapid termination of ISD. This
was taken as evidence for rapid expansion cooling of hot “early” plume formed in MALDI. CHCA was hotter than DHB for [Y6 + H]+ while the matrix effect was insignificant for BTPP. The “early” plume temperature estimated utilizing previous kinetic results
was 800–900 K, versus 400–500 K for “late” plume. The results support our previous finding that the temperature of peptide
ions interrogated by tandem mass spectrometry was lower than most rough estimates of MALDI temperature. 相似文献
17.
Josep M. Oliva 《Theoretical chemistry accounts》1999,103(1):1-8
Modern valence-bond theory, in its spin-coupled form, is used to study the electronic structure of the transition structures
in the Cope rearrangement. It is found that the transition structure described by a “chair” geometry with a “6-in-6” CASSCF/6-31G* wave function is clearly aromatic while the CASSCF/6-31G*“boat” transition structure corresponds more closely to two weakly interacting allyl radicals. Moreover, there is a striking
resemblance between the CASSCF chair transition structure and the benzene molecule, arising from the modern valence-bond analysis
in terms of Rumer spin functions. In agreement with previous works, dynamical correlated wave functions show shorter interallylic
distances in the optimized transitions structures. The use of spin-coupled wave functions on the latter geometries results
in diradical and aromatic character for the chair and boat transition structures, respectively.
Received: 13 October 1998 / Accepted: 30 December 1998 / Published online: 7 June 1999 相似文献
18.
On the basis of a transition state conformation analysis, an attempt was made to explain the high chemoselectivity of intramolecular [4 + 2] cycloaddition in 3-alkyl-2,6-difuryl-N-maleylpiperidin-4-ones. It was shown that the thermal Diels–Alder reaction in these piperidine derivatives takes place through the “boat” conformation and leads to the formation of hydrogenated 1-alkyl-4-(2-furyl)-2H-8,10a-epoxy-pyrido[2,1-a]isoindol-2-ones. The alternative regioisomers, 3-alkyl-4-(2-furyl)-2H-8,10a-epoxy-pyrido[2,1-a]isoindol-2-ones, are hardly formed at all. At the same time, the intramolecular Diels–Alder reaction in the isostructural 3-alkyl-N-allyl-2,6-difurylpiperidin-4-ones, takes place non-regioselectively from the “chair” conformation. 相似文献
19.
Yuri Pleskov Alik Tameev Valentin Varnin Irina Teremetskaya 《Journal of Solid State Electrochemistry》1998,3(1):25-30
The drift mobility of nonequilibrium holes injected in undoped polycrystalline diamond films was determined, by a transit-time
technique, as ca. 10−3 cm2/(V s). This hole mobility is three orders of magnitude lower than the “equilibrium” mobility in boron-doped diamond films
[0.1–1 cm2/(V s)], determined from the films' dc conductivity. This difference is explained by the effect of a nonequilibrium charge
carrier trapping during the carrier transport in polycrystalline diamond.
Received: 3 December 1997 / Accepted: 9 April 1998 相似文献
20.
Horst Fr. Schröder Wilhelm Gebhardt Mario Thevis 《Analytical and bioanalytical chemistry》2010,398(3):1207-1229
Municipal wastewater has been examined for steroids, β2-agonists, stimulants, diuretics, and phosphodiesterase type V inhibitors (PDE type V inhibitors), which are “dual-use-drugs”
applied either as anabolic, doping, and lifestyle drugs or for treatment of diverse diseases. To identify their origin, fitness
centre discharges under suspicion of being point sources and sewage-treatment plant feed and effluents were sampled and concentrations
determined. Sensitive and selective methods for determination and quantification based on solid-phase extraction (SPE) followed
by high-performance liquid chromatography–high resolution mass and tandem mass spectrometry (HPLC–(HR)MS and HPLC–MS–MS) were
developed and established for analysis of these compounds in wastewater and to assess their effect on the environment. The
methods developed enabled quantification at trace concentrations (limit of quantification (LOQ): 5 ng L−1). Of the steroids and stimulants under investigation, testosterone, methyltestosterone, and boldenone or ephedrine, amphetamine,
and MDMA (3,4-methylendioxy-N-methylamphetamine) were observed at up to 5 μg L−1 (ephedrine). Of the β2-agonists salbutamol only, and of the diuretics furosemide and hydrochlorothiazide were confirmed in the extracts. Quite high
concentrations of the PDE type V inhibitors sildenafil, tadalafil, and vardenafil and their metabolites were confirmed in
fitness centre discharges (sildenafil: 1,945 ng L−1) whereas their concentrations in municipal wastewater did not exceed 35 ng L−1. This study identified anabolic and doping drugs in wastewater for the first time. Results obtained from wastewater treatment
plant effluents proved that these “dual-use-drugs”, with the exception of hydrochlorothiazide, were mostly eliminated. 相似文献