bluuebunny/crossref_metadata_2025_split huggingface dataset:
The ion‐trap mass spectrometer in ion structure studies. The case of [MH]+ ions from chalcone
Authors: Ardanaz C. E. , Traldi P. , Vettori U. , Kavka J. , Guidugli F. 
Published: May 2005

AbstractIon‐structure investigation of the [MH]+ ions from chalcone has been carried out by collision experiments performed with an ion‐trap mass spectrometer (ITMS), operating with the application of a supplementary RF voltage. The data so obtained, together with those achieved by comparison with labelled model compounds, have led to a clear identification of the [MH]+ ion structure, proving the high potentialities of the ITMS in such a field.
The methane dication revisited
Authors: Nagesha K. , Marathe V. R. , Mathur D. 
Published: May 2005

AbstractAll‐electron, ab initio molecular orbital calculations have been performed on electronic states of CH using perturbative configuration interaction procedures and large sets of Gaussian basis functions with a view to attempting reconciliation between contemporary quantum‐chemical information and different sets of experimen‐tal data from charge‐stripping, threshold photoionization, and double‐charge‐transfer mass spectrometry. Metastable electronic states of CH are predicted for D4h and D2d symmetries, with charge‐stripping experiments likely to populate spin singles of the former symmetry. Investigation of the dissociation of CH (D4h) to CH (D3h)+ H+ along the C2v symmetry pathway indicates that theoretical and experimental data on metastable states of this dication are in accord only if non‐Frank‐Condon transitions are postulated.
Analysis of a mass‐analysed ion kinetic energy peak profile for a metastable ion decomposition occurring in a collision cell floated at high voltage
Authors: Kim Young Hwan , Kim Myung Soo 
Published: May 2005

AbstractA numerical method has been developed to obtain the kinetic energy release distribution from a mass‐analysed ion kinetic energy peak profile for a metastable ion decomposition occurring in a collision cell floated at high voltage. The method has been applied to the unimolecular dissociation of the tert‐butylbenzene molecular ion. The kinetic energy release distribution thus obtained was nearly invariant to the applied voltage. Peak tailing due to dissociation in the field region could be reproduced adequately The method may be useful for the investigation of unimolecular ion decomposition in narrow time‐ and energy‐windows.
A new matrix for fast‐atom bombardment analysis of corrins
Authors: Staempfli A. A. , Schlunegger U. P. 
Published: May 2005

Abstract2,3‐dihydroxypropyl benzyl ether, a glycerol derivative, is a suitable matrix for fast‐atom bombardment analysis. It has been shown to be superior to glycerol and thioglycerol for the detection of molecular ions of cobyrates.
Comparison between a quadrupole and an emission spectrometer in the determination of low level 15N abundance
Authors: Cervelli S. , DiGiovanni F. , Ferrari S. 
Published: May 2005

AbstractThe use of stable isotopes in ecosystem studies is increasing, due to the possibility of obtaining information on source/sink balances in the environment. Carbon, nitrogen oxygen and sulphur all have more than one stable isotope, and their isotopic concentration can be measured with precision by mass spectrometry. The use of this technique in environmental studies is not yet extensive, due both to the lack of a chemical and geochemical background of many ecologists, and the high cost of mass spectrometers. In this paper we report some experiments on the determination of 15N abundance in low ‐enriched nitrogenous materials (0.366–0.998% abundance) by two comparable low‐cost instruments: an emission spectrometer (Jasco NIA I) and a quadrupole mass spectrometer (Rial QM 130‐CS).
Distinguishing N‐ and C‐terminus ions for mass spectrometry sequencing of proteins without prior degradation
Authors: Aaserud David J. , Little Daniel P. , O'Connor Peter B. , McLafferty Fred W. 
Published: May 2005

AbstractIdentifying complementary pairs of fragment ions, b‐type vs y‐type, is a key step in mass spectral sequencing of proteins without degradation prior to ionization. Observations that b‐type ions tend to be less stable than y‐type have been extended to carbonic anhydrase (29kDa) as a model protein. Infrared multiphoton dissociation (IRMPD) of 24+, 27+, 30+ molecular ions shows y‐type ions from complementary pairs require, on average, 27% longer irradiation times for onset of abundance decrease, while in nozzle/skimmer dissociation of all charge states, y‐type ions require a 20% higher potential difference. In some cases, b‐ion dissociation appears to accompany its formation, as its rate of increase with increasing energy deposition is far less than that of its y‐complement.
Identification of organogermanium compounds as matrix complexes in fast‐atom bombardment mass spectrometry
Authors: Akiba Mitsuo , Sasaki Yoshinori , Kakimoto Norihiro , Ohnishi‐Kameyama Mayumi , Nagata Tadahiro 
Published: May 2005

AbstractThe application of aqueous matrices to fast‐atom bombardment mass spectrometry enables the detection of several organogermanium compounds as specific complexes with matrices. In the positive‐ion mode, the organogermanium compounds showed a dominant ion [M+matrix‐3 · H2O+H]+ whose dehydration involved atoms attached to the germanium atom. On the other hand, two types of fragmentation were observed in the negative‐ion mode The first was a group of compounds, with a carboxy group, that formed a lactone ring and showed a dominant ion at [M+matrix ‐3 · H2O‐H]−. The other group, without carboxy, attached another matrix molecule and showed a dominant fragment ion at [M+2 · matrix‐3 · H2O‐H]−. The investigation of these complex structures was performed using various matrices and D2O treatment.
Sequencing of oligonucleotides using high performance liquid chromatography and electrospray mass spectrometry
Authors: Glover Robert P. , Roberts Gordon C. K. , Sweetman Gavain M. A. , Farmer Peter B. 
Published: May 2005

AbstractWe report the sequence analysis of an oligodeoxyribonucleotide by electrospray mass spectrometry (ES‐MS). For full sequence analysis of the oligomer, d(CGTAGCTACG), an enzyme digestion step followed by off‐line high performance liquid chromatography was used. For ES‐MS analysis, introducing the sample in an imidazole buffer with 70% acetonitrile increased the electrospray ion currents and helped reduce sodium‐adduct ion peaks.
Visualization of craters in a Langmuir–Blodgett film from the impact of 23 MeV C ions
Authors: Tomaschko Ch. , Schurr M. , Berger R. , Saemann‐Ischenko G. , Voit H. , Brunelle A. , Della‐Negra S. , Lebeyec Y. 
Published: May 2005

AbstractAtomic force microscopy (AFM) images taken from an Fe‐arachidate Langmuir‐Blodgett film irradiated with 23 MeV fullerene ions gives clear evidence that craters are formed as a result of the cluster‐ion impact. The crater diameter fits into a systematic formula already found for atomic ions. The AFM images indicate that even the largest molecular ions desorbed stem from the crater volume.
Endgroup analysis of polyethylene glycol polymers by matrix‐assisted laser desorption/ionization Fourier‐transform ion cyclotron resonance mass spectrometry
Authors: de Koster Chris G. , Duursma Marc C. , van Rooij Gerard J. , Heeren Ron M. A. , Boon Jaap J. 
Published: May 2005

AbstractFourier‐transform ion cyclotron resonance mass spectrometry (FTICR‐MS) by external injection of matrix‐assisted laser desorbed and ionized (MALDI) polymers offers good possibilities for characterization of low molecular weight homopolymers (MW range up to 10 kDa). The molecular masses of the molecular weight distribution (MWD) components of underivatized and derivatized (dimethyl, dipropyl, dibutyl and diacetyl) polyethylene giycol (PEG) 1000 and 4000 were measured by MALDI‐FTICR‐MS. These measurements have been performed using a commercial FTICR spectrometer with a home‐built external ion source. MALDI of the samples with a 2,5‐dihydroxybenzoic acid matrix in a 1000: 1 matrix‐to‐analyte molar ratio produces sodiated molecules in a sufficient yield to trap the ions in the ICR cell. The masses of the molecular weight distribution of PEG components were measured in broad‐band mode with a mass accuracy of < 5 ppm in the mass range around 1000 u and within 40 ppm accuracy around 4000 u. From these measurements, the endgroup mass of the polymer was determined by correlation of the measured component mass with the degree of polymerization. The masses of the PEG endgroups have been determined within a deviation of 3–10 millimass units for the PEG1000 derivatives and 10–100 millimass units for the PEG4000 derivatives, thus confirming the identity of the distal parts of the model compounds.
Mass spectrometric methodologies in plant analysis: The case of flavonols in Sedum telephium L. Juice
Authors: Mulinacci N. , Vincieri F. F. , Baldi A. , Romani A. , Favretto D. , Traldi P. 
Published: May 2005

AbstractNegative‐ion fast‐atom bombardment mass spectrometry together with precursor and product‐ion spectroscopies has been validly employed in the identification of six flavonol glycosides present in the juice of Sedum telephium leaves. The proposed technique proved to be a valuable alternative to the combination of high performance liquid chromatography and mass spectrometry in the analysis of the complex polyphenol mixtures present in some medicinal plants.
Surface studies of conversion coated steel after corrosion induced paint deadhesion
Authors: deVries J. E. , Riley T. L. , Holubka J. W. , Dickie R. A. 
Published: May 2005

AbstractSecondary ion mass spectorscopy (SIMS) and scanning electron microscopy (SEM) have been used to characterize the surface composition and morphology of zinc‐phosphated steel before application of organic coatings and after corrosion‐induced delamination of these coatings. Imaging SIMS and SEM results confirm the presence of a cystalline zinc‐iron‐phosphate layer on the phosphated steel before coating application. During the corrosion process, dissolution of the crystal structure occurs between the initial corrosion site and the progressing edge of corrosion induced delamination. Beyond this edge the crystal structure remains intact.
Surface chemistry of a microcoated energetic material, pentaerythritoltetranitrate (PETN)
Authors: Worley C. M. , Vannet M. D. , Ball G. L. , Moddeman W. E. 
Published: May 2005

AbstractA microcoating technique was used to apply a polymer to an energetic explosive material. The explosive was pentaerythritoltetranitrate (PETN), and the coating was a copolymer consisting of vinylchloride/trifluorochloroethylene in a 1.5/1.0 molecular ratio. X‐ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS) were used to study the surface and interfacial chemistry of PETN powders and pellets made from compressed powders having either 0.5 or 20 wt% coating. Two simple models were used to discuss the nature of the copolymer film on the PETN. Model I shows the copolymer completely coating PETN; Model II depicts the copolymer as only partially covering PETN. Model II was applicable in explaining the 0.5 and 20 wt% microcoating of powders, as well as the 0.5 wt% coated pellets. However, the pellets with 20 wt% coating showed the copolymer to completely coat PETN (Model I), suggesting copolymer redistribution during pelletization. XPS and ISS results showed the copolymer film to be thin. An XPS expression modified to accommodate ISS data was developed for the calculation of the average copolymer thickness of PETN. The thicknesses were determined to be 10 Å and 6 Å for 0.5 wt% coated PETN powders and pellets, respectively. Bonding between the copolymer and PETN was concluded to be mechanical.
Applications of in situ SIMS during processing of electronic materials
Authors: Webb A. P. , Smith J. A. 
Published: May 2005

AbstractAn in situ SIMS system is described that is capable of providing accurate and reliable control in determining the termination of processes whilst etching through multi‐layer structures. The instrumentation is described and how progressive alterations have been implemented to improve the sensitivity. Various applications are described which show the wide range of material systems that have already been addressed.
SiO2 in 6:3 (stishovite) and 4:2 Co‐ordination—Characterization by core level spectroscopy (XPS/XAES)
Authors: Finster J. 
Published: May 2005

AbstractA comprehensive XPS/XAES investigation of the dense 6:3 co‐ordinated SiO2 polymorph stishovite in comparison with different SiO4/2 samples and Si was carried out for the first time. By evaluation of initial state and final state shift contributions, effective charges and extra‐atomic relaxation energies were determined and discussed in the context of the electronic structure for different co‐ordination numbers. The reduced binding energies of Si and O lines for stishovite are due to the higher extra‐atomic relaxation energy in comparison to SiO4/2, which correlates with the higher dielectric constant and the lower gap energy in SiO6/3. The effective charges are only slightly higher in stishovite than e.g. in quartz.
Calculations of electorn inelastic mean free paths. II. Data for 27 elements over the 50–2000 eV range
Authors: Tanuma S. , Powell C. J. , Penn D. R. 
Published: May 2005

AbstractWe report calculations of electron inelastic mean free paths (IMFPs) for 50–2000 eV electrons in a group of 27 elements (C, Mg, Al, Si, Ti, V, Cr, Fe, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Re, Os, Ir, Pt, Au and Bi). This work extends our previous calculations (Surf. Interface Anal. 11, 57 (1988)) for the 200–2000 eV range. Substantial variations were found in the shapes of the IMFP versus energy curves from element to element over the 50–2000 eV range and we attribute these variations to the different inelastic scattering properties of each material. Our calculated IMFPs wee fitted to a modified form of the Bethe equation for inelastic electron scattering in matter; this equation has four parameters. These four parameters could be empirically related to several material parameters for our group of elements (atomic weight, bulk density and number of valence electron per atom). IMFPs and those initially calculated was 13%. The modified Bethe equation and our expressions for the four parameters can therefore be used to estimate IMFPs in other materials. The uncertainties in the algorithm used for our IMFP calculation are difficult to estimate but are believed to be largely systematic. Since the same algorithm has been used for calculating IMFPs, our predictive IMFP formula is considered to be particularly useful for predicting the IMFP dependence on energy in the 50–2000 eV range and the material dependence for a given energy.
Laser Raman and XPS analyses of molybdenum–rare earth oxide catalysts
Authors: Nieto J. M. López , Corberán V. Cortés , Fierro J. L. G. 
Published: May 2005

AbstractLaser Raman spectroscopy (LRS) and x‐ray photoelectron spectroscopy (XPS), combined with x‐ray diffraction (XRD), have been used to characterize the phases in Mo–RE–O (RE = Sm, Tb, Yb) systems. Two clearly differentiated composition regions were observed, namely the RE‐rich region (x < 0.5–0.6, where x represents the Mo/(Mo + RE) atomic ratio), in which the RE oxide was always present as a separate phase, and the Mo‐rich region (x > 0.6) in which MoO3 appeared as a separate phase. The broadening of the Raman bands in the RE‐rich region is indicative of the presence of ill‐defined structures. However, as the RE oxide content increased, crystalline molybdates with decreasing Mo/RE ratios were found in each system. XPS surface composition was roughly similar to that of the bulk for the Mo–Sm–O and Mo–Yb–O series, while relevance of MoO3 and molybdate phases in the Mo‐rich composition regions is discussed in the context of allylic oxidation of light olefins.
Partial intensity analysis (PIA) for quantitative electron spectroscopy
Authors: Werner Wolfgang S. M. 
Published: May 2005

AbstractAn approach is developed to separate the spectral contributions of electrons that have experienced a certain number of inelastic collisions and together constitute the observable lineshape in AES/XPS. The only assumption concerning the emission process that is made in this general approach is that energy losses and deflections occur separately. This means that the method can account for elastic scattering with arbitrary sophistication, while it can also be applied to spectra from samples exhibiting surface roughness or specimens with an arbitrary depth profile and even single crystals where diffraction effects dominate the peak intensities. If the details of the emission process are properly understood, such a so‐called partial intensity analysis may serve to assess the structural characteristics of an unknown specimen. Conversely, if the sample structure is known, it can be employed to assess experimentally the details of the emission process (elastic scattering, roughness, diffraction). At any rate, a partial intensity analysis allows proper background correction of the spectral lineshape to be performed if this is the ultimate aim of analysis. This again holds true without regard to the emission process and is possible without any kind of fitting or ad hoc assumptions. On a very similar basis, a method is derived to gain accurate information about the inelastic transport characteristics from reflection experiments in the case when the other quantities governing the particle transfer are known. The results are general in that the starting point of the method, i.e. the yield equation, in principle also describes the fundamentals of other techniques employing particle–solid interaction.
Advances in the use of molybdenum compounds as smoke suppressants for PVC
Authors: Moore Fred W. , Weber Thomas R. , Tsigdinos George A. 
Published: May 2005

AbstractMolybdenum‐based compounds are effective smoke suppressants for rigid and flexible polyvinyl chloride formulations, both unfilled and filled with calcium carbonate and alumina trihydrate. These compounds, two of which are new compounds based on zinc molybdate with or without a phosphite synergist, are useful as is or extended onto core materials such as clay or talc. The addition of molybdenum‐containing additives to flexible PVCs containing antimony trioxide usually raises the oxygen index and thus improves flame retardancy. Tests indicate that molybdenum acts as a flame and smoke suppressant in the solid phase.
Antimony‐based flame retardant systems in plasticized polyvinyl chloride compounds
Authors: Furnivall James C. , Kupfer Alan D. , Irvine John L. 
Published: May 2005

AbstractA method of choosing the most effective way to meet specific flame retardant requirements in polyvinyl chloride compounds, which uses flammability tests based on oxygen indexes, shows that antimony‐based and non‐antimony retardants perform as well as commonly used antimony oxide retardants, and at a reduced cost.
Marketplace synergies for PVC additives—how the supplier alliance is working in PVC markets
Authors: Goodman Donald 
Published: May 2005

AbstractPVC is the only major plastic that needs additives to enhance its properties. Without additives, PVC would not enjoy its robust business and wide range of applications. This paper considers how additive suppliers have been able to bring out the best in PVC in an alliance that has been mutually beneficial. The alliance also comes with challenges to meet new and expanded regulations, as well as opportunities to develop tomorrow's materials. Some emerging concepts of “Responsible Care” are presented, which concern how resin and additive suppliers will have to provide product stewardship of compounds and products throughout their useful application lifetimes and provide options for proper disposal.
An evaluation of the suitability of X‐ray fluorescence spectroscopy in the analysis of complex alloy systems
Authors: Bäckerud L. 
Published: May 2005

AbstractAn attempt has been made to evaluate on the basis of simple physical theories the principal possibilities and limitations of the X‐ray fluorescence method in determining both principal components and other alloying elements as well as impurities in relatively complex alloy systems. The text refers specifically to the analysis of copper‐based alloys, but the principles are general ones and the arguments can easily be applied to other systems.
Notes and comments: The training of X‐ray spectroscopists
Authors: Chessin H. 
Published: May 2005

AbstractOne of the current problems in the application of the X‐ray spectrometer is the training of operators in the use of instrumentation and techniques. One of the usual consequences of rapid expansion in the use of any instrumental procedure is the lack of general experience and expertise, and in this X‐ray spectrometry is no exception. As a technique it has only recently been introduced into the syllabus of the appropriate university course of study and, at the present time, this only at a very few universities. Training in X‐ray spectrometry has therefore become very much an extra‐mural course of study and among the more successful groups to offer courses in the U.S.A. has been the State University of New York at Albany. The following short report by Professor Chessin gives an informal description of the background of his ‘Clinics’ and describes some of his experiences.
The loss of br from thin‐film samples during X‐ray fluorescence analysis
Authors: O'Connor B. H. , Kerrigan G. C. , Hinchliffe P. 
Published: May 2005

AbstractThe loss of Br during X‐ray fluorescence analysis presents problems in thin‐film determinations such as those employed in this laboratory for environmental particulate samples and in machine calibration with spotted filter standards. The occurrence of Br losses is easily overlooked unless appropriate measures are taken during calibration and analysis. Losses may be reduced to c. 2% by sealing the samples with adhesive tape, and by limiting the duration of the analysis to several minutes.
Identification of unconverted oxide phases in a synthetic clay mineral by scanning electron microscopy and the x‐ray microprobe
Authors: Patel Mahendra 
Published: May 2005

AbstractThe difficulty of identifying unconverted oxide phases, present in synthetic clay minerals, by classical techniques is discussed. It is shown that scanning electron microscopy, combined with the x‐ray microprobe, is very effective in such a study. Some representative micrographs of oxide phases in a synthetic vermiculite are presented.
Quantitative electron probe microanalysis in the system Fe–Sn–C using the Claisse–Quintin relation
Authors: Fredriksz W. , Koster H. , Kolster B. H. 
Published: May 2005

AbstractQuantitative interpretation of EPMA measurements was required for the construction of the Fe–Sn–C phase diagram. This involved the conversion of measured x‐ray intensities into concentrations, which is difficult for a light element (such as C) being present among heavier elements (Fe and Sn). To meet this problem, firstly the various intensity–concentration conversion methods from the literature have been studied and are briefly surveyed. The Claisse–Quintin relation with constant influence coefficients was selected as the algorithm for multiple regression purposes, which was applied to reference standard data. Calibration functions are obtained for Sn and C, which are used in a simple iteration procedure. This procedure has been used for the conversion of Sn and C x‐ray intensities into concentrations. The method shows a relative accuracy of about 5%.
Spectral distribution of backseattered electrons: Application to electron probe microanalysis
Authors: Del Giorgio M. , Trincavelli J. , Riveros J. A. 
Published: May 2005

AbstractThe parameters ϕ0 and γ0 of the Gaussian model for the depth distribution of characteristic x‐ray production ϕ(ρz) were evaluated using an analytical expression for the energy distribution of backscatrered electrons. The expressions obtained were compared with those which do not take into account this distribution. A test of the usefulness of both models was performed for microanalysis corrections.