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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 405-410 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Stationary phases of polysiloxane-type degrade in acidic solution ; Several salt traces affect stability at high temperature NaCl on Duran-5O: no effect at 260°C ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of polysiloxanes have been shown to be sensitive to acids when dissolved in chloroform.At 26O°C polysiloxanes were found to degrade under the influence of several compounds used or produced during the preparation of glass capillary columns.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 69-70 
    ISSN: 0935-6304
    Keywords: Gas Chromatography ; Stationary phases, chemical stability in solutions ; SE 30, SE 54 in chloroform or toluene show rapid depolymerization (HCL-, Tetramethylammoniu hydroxide-traces responsible) ; Solutions with decreased molecular weight of silicon phase give decreased film thickness (Hg plug technique) and increased tailing in glass capillary impregnation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 906-912 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A method of deriving peptide sequence information using partial acid hydrolysis in combination with accurate mass measurements and immonium ion analysis provided by high-resolution plasma desorption mass spectrometry has been developed. The technique is very simple in terms of the chemistry and involves a short-time (3-30 min) incubation of the peptide in 1N-6N HCl at 100-110°C with subsequent mass spectrometric analysis. Partial acid hydrolysis is found to produce sequence-specific segments, often ladder-like, although not always a complete set. Two application examples of the method are given: the linear peptide bradykinin and desmopressin, a peptide with an internal S—S bond and a non-amino-acid constituent. The technique has proved to be particularly useful in cases where some a priori information on the peptide structure was already known or where the automated Edman degradation technique might yield erratic results or not work at all.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1968), S. 323-329 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: It is shown that in porphin derivatives the McLafferty rearrangement occurs preferentially in even electron systems, in fact with high relative abundance starting from M2+, but less favorably in ions formed by elimination of a radical. Starting from this observation the formulation of a general scheme for the McLafferty rearrangement is attempted.
    Notes: Es wird gezeigt, daß in Porphin-Derivaten die McLafferty-Umlagerung bevorzugt in geradelektronischen Systemen abläuft. und zwar mit großer relative Häufigkeit ausgehend von M2+, jedoch weniger begünstigt in Ionen, die durch Radikalabspaltung entstanden sind. Von dieser Beobachtung ausgehend wird ein allgemeines Schema für die McLafferty-Umlagerung vorgeschlagen.
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 12 (1989), S. 460-463 
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 13 (1984), S. 69-77 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A study of the low-energy region (below 1. 5 keV) of energy dispersive x-ray spectra has been carried out. Firstly, because some counting systems do not provide a reliable dead time correction, a new method of dealing with the problem is given. Next, the effects of different positioning of the energy discriminator within the analyser circuitry are discussed with reference to the consequences for light element analysis. Electronic noise counts can present a problem for analysis of x-rays of less than 300 eV and a straightforward method for noise removal is described. Finally, an unexpected artifact in the spectrum below 500 eV is identified; its size is related to the total number of counts in the spectrum and a practical method of dealing with it is demonstrated. Once the above factors have been taken into account a low energy spectrum is produced, consisting solely of characteristic x-ray lines and a true continuum background.
    Additional Material: 2 Ill.
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  • 7
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A comparison has been made between light element (5 〈 Z 〈 11) analyses performed using energy-dispersive and wavelength-dispersive spectrometry. It is shown that, provided appropriate spectrum processing methods are adopted, the two sets of data agree to within 2-3%. Since there is every reason to believe the wavelength-dispersive measurements are accurate, this demonstrates the feasibility of carrying out quantitative light element analysis by the energy-dispersive technique. The minimum concentrations of carbon, nitrogen and oxygen which can be detected in selected matrices have been established and it is shown that sensitivities of better than 0.5 wt% are achievable if the electron probe voltage is carefully chosen.
    Additional Material: 12 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 21 (1992), S. 27-35 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new correction method for obtaining quantitative electron probe microanalysis results is described. It utilizes data provided by Monte Carlo simulations and tracer measurements to obtain a detailed picture of the way in which the x-ray emission process is influenced by the relevant experimental parameters. Then empirical equations are derived which model the intensity of x-ray emission for an extremely wide range of experimental conditions, encompassing electron beam energies from 5 to 40 keV, characteristic x-ray wavelengths from 11.4 to 0.08 nm, angles of electron incidence from 90° to 40° and elements ranging from beryllium to uranium in the Periodic Table. The method treats separately, as with the traditional approach, the effects of atomic number difference in specimen and standard, x-ray absorption and x-ray fluorescence. The correction method was tested on an extensive range of microanalysis data and shown to work well under all conditions, providing chemical compositions which are accutate to within a few percent relative. The capability of handling ultra-light element (beryllium to sodium) analysis is particularly impressive and the r.m.s. error of 3.8% for carbon analysis on carbides is very close to the errors incurred in measuring actual x-ray intensities. The correction program is currently being developed for commercial use on IBM-compatible computers and the final stage in the evolution of the universal correction will be to extend it to deal with the analysis of thin surface films.
    Additional Material: 5 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 12 (1983), S. 2-7 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Two common methods of applying dead-time corrections in EDS systems, both of which are carried out internally in the electronics, are examined. The Barnhart method shows serious discrepancies when making dead-time corrections and in certain cases no correction is made at all. The problem is associated with the reliance on the fast amplifier to count all x-rays collected by the detector. In practice, however, the fast amplifier does not always succeed in carrying out this function since x-rays with energies 〈 1500 eV may fall below its threshold level. The problems become worse when a formvar window is substituted for beryllium since a greater proportion of low energy x-rays can now reach the detector. The magnitude of the discrepancy is shown also to be a function of specimen and electron accelerating voltage. Similar experiments with an EDS system using the Covell method show that no such discrepancies arise.
    Additional Material: 6 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 1 (1973), S. 513-519 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study of the infrared and Raman spectra of single crystals and powders of ZnGa2O4 yields the following k = 0 phonon frequencies: 175 cm-1 (T1u), 328 cm-1 (T1u), 420 cm-1 (T1u), 570 cm-1 (T1u), 467 cm-1 (T2g), 611 cm-1 (T2g), 638 cm -1 (Eg) and 714 cm-1 (A1g).The results are compared with the frequencies of the vibronic sidebands of the Cr3+ R line emission as observed in ZnGa2O4: Cr3+. It is found that the strogest vibronics of the R lines are due to coupling of the Cr3+ electrons with the T1u modes of the ZnGa2O4 lattice, especially with the two higher frequency T1u modes.
    Additional Material: 2 Ill.
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