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  • 1
    Electronic Resource
    Electronic Resource
    Immunochemistry of sperm whale of myoglobin. IX. Specific interaction of peptides obtained by cleavage at arginine peptide bonds (1971)
    s.l. : American Chemical Society
    Biochemistry 10 (1971), S. 1756-1762 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00786a004
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  • 2
    Electronic Resource
    Electronic Resource
    Observations and analysis of resonant laser ablation of GaAs (1991)
    Springer
    Applied physics 53 (1991), S. 34-38 
    Details
    ISSN: 1432-0649
    Keywords: 32.80 ; 32.90+1 ; 79.20.Ds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Laser ablation of solid GaAs samples has been studied using one tunable pulsed dye laser. At relatively low laser power, enhancements of up to several hundred times have been observed in the yield of resonantly ionised Ga using laser wavelengths corresponding to the atomic transition 42 P 1/2-42 D 3/2. The influences of laser power and target geometry, on the ion yield and spectral profile, are discussed. It is argued that the resonant excitation and ionisation processes occur in the gas phase of the atoms ablated from the sample surface, and the observed asymmetric spectral profile results from laser-induced collisional processes, e.g., optical collisions, under conditions of relatively high atomic density in the interaction region. Potential applications are foreseen for resonant laser ablation in trace analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325480
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis of dirhodium[3H]tetraacetate (1988)
    Springer
    Journal of radioanalytical and nuclear chemistry 128 (1988), S. 377-385 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Realizing a need for labeled dirhodium tetraacetate [Rh2/OAc/4] for binding studies by the equilibrium dialysis procedure, we have established a method for the preparation and purification of [3H]Rh2/OAc/4. This is obtained with a tritium label of a sufficiently high specific activity in the methyl group of acetate residues. The method consists of replacement of the existing acetate bridge by [3H]OAc−. A typical preparation involves refluxing Rh2/OAc/4 with [3H]NaOAc in dry ethanol at 80°C for 6 h. The reaction time is critical for obtaining the product with a high specific activity. A simple purification of reaction products yields the compound of interest with a high specific activity, i. e., 315±10 Ci per mol of Rh2/OAc/4 and in satisfactory yield /87% of the starting material., This labeled material can be synthesized with greatly increased specific activity /of tritium in acetate groups/ by employing [3H]NaOAc without prior dilution. The labeled Rh2/OAc/4 is stable and yields a characteristic product with adenylic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02205192
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  • 4
    Electronic Resource
    Electronic Resource
    Laser-induced collisional processes in resonant laser ablation of GaAs (1992)
    Springer
    Applied physics 54 (1992), S. 71-75 
    Details
    ISSN: 1432-0649
    Keywords: 32.80−t ; 32.90.+a ; 79.20Ds ; 34.90.+q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The transitions between the multiplets of 42 P → 42 D and 42 P → 52 P in Ga have been studied by observing the ions produced in the ablation of a GaAs surface using a tunable dye laser. The asymmetric spectral profiles of the 42 P → 42 D transitions, and the large differences in laser power dependence of the ion yields for the different resonant schemes were observed and analysed. The experimental data are interpreted as resulting from laser-induced collisional processes, especially, from optical collisional excitation and energy-pooling ionisation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331736
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  • 5
    Electronic Resource
    Electronic Resource
    Formation of atomic hydrogen in matrix-assisted laser desorption ionization (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 829-832 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Despite the widespread use of matrix-assisted laser desorption ionization, the processes involved in ion formation have yet to be satisfactorily explained. Several protonation processes have been suggested as possible methods for the creation of the analyte ions. In this work the existence of neutral hydrogen atoms in the ablation plume is reported. These are selectively ionized from the ground state through a (2+1) multiphoton resonant excitation scheme. The mass spectra at different delay times between the ablation and the post-ablation-ionization lasers have demonstrated the existence of hydrogen atoms with high velocities in the ablated plume.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290081007
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  • 6
    Electronic Resource
    Electronic Resource
    A tandem reflectron time-of-flight mass spectrometer for the investigation of laser photofragmentation of molecular ions (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 761-766 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A tandem reflectron time-of-flight mass spectrometer has been constructed for the investigation of laser photofragmentation of selected molecular ions. Ions are generated by an ablation laser and attracted by ion optics into the field-free flight region of a reflectron time-of-flight mass spectrometer. Laser photofragmentation of selected molecular ions takes place at the turn-around point of ions in the reflectron. Fragmentation mass calibration, parent ion selection, ion collection effects, reflectron field effects and the mass resolution of this tandem reflectron time-of-flight mass spectrometer are described. Furthermore it is shown that laser parameters may be used to control the fragmentation pattern.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290090908
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  • 7
    Electronic Resource
    Electronic Resource
    The characteristics of resonant laser ablation for surface analysis (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 18 (1992), S. 576-578 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Resonant laser ablation (RLA) is a technique in which a pulsed tunable laser beam is directed at grazing incidence to the surface of a sample, such that neutral atoms are first ablated and then resonantly ionized by the same pulse. In this short communication the important characterstics of RLA are presented. From the results already obtained, detection levels of a few parts per million for aluminium in steel samples have been determined. The potential of RLA as a surface analysis technique is assessed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740180721
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of heat treatment on dielectric relaxation of polyacrylonitrile: Reversible thermally induced structural change (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 3599-3608 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of heat treatment on the dielectric relaxation of polyacrylonitrile (PAN) was studied. Dielectric measurements, in the frequency range 0.1-100 kHz and temperature range 30-170°C, on PAN heat treated at two temperatures (120 and 160°C) and the untreated PAN are reported. The loss peak height, the dielectric relaxation strength, loss peak width, and the loss peak temperature were found to vary systematically with the temperature of the heat treatment. The changes in dielectric relaxation produced by heat treatment at the higher temperature (i.e., 160°C) were considerably less than those produced by heat treatment at 120°C. The results are discussed and attributed to the variation of the degree of bound nitrile groups (through their dipole-dipole interaction) with heat treatment temperature. Heat treatment of the higher temperature (160°C) results in lower degree of bound nitrile groups in the structure than heat treatment at the lower temperature (120°C).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070261108
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of heat treatment on the dielectric relaxation of polyacrylonitrile. III. Role of duration of heat treatment (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 2745-2754 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dielectric relaxation of polyacrylonitrile (PAN) heat-treated at 120°C in vacuum for durations varying from 4 to 24 h is studied in order to investigate the effect of the duration of heat treatment. Decrease in dielectric constant increment and loss peak height and an increase in relaxation temperature on heat treatment are observed at all durations of heat treatment. At the studied temperature of heat treatment the observed changes in dielectric relaxation were found to increase with duration of heat treatment showing maxima at a 16 h duration and then a decrease at a higher duration of heat treatment. The results are discussed in terms of the variation of degree of intermolecularly bound nitrile groups with the duration of heat treatment. Glass transition temperature calculated from the dielectric data, through WLF theory, showed a variation, similar to that of the degree of bound nitrile groups, with duration of heat treatment. The observed variation of Tg is attributed to the interlinking effect produced by the bound nitrile group pairs on the segmental mobility.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1983.070280906
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of heat treatment on the dielectric relaxation of polyacrylonitrile. II. Heat treatment under vacuum and in air (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 4101-4114 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dielectric relaxation, infrared spectra, and X-ray diffraction data of polyacrylonitrile (PAN) heat treated at 120°C in air and under vacuum and of the untreated PAN are reported. The heat treatment resulted in (1) lowering of dielectric constant increment, dielectric dissipation factor, and increase in relaxation temperature and glass transition temperature; (2) lowering of the intensity of —C≡N stretching band in the infrared spectra; and (3) increase in degree of order of the X-ray diffraction results. The changes produced by heat treatment under vacuum are found greater than those produced by heat treatment in air, which suggests that the observed effect is not caused by chemical changes in the PAN molecule under heat treatment. Interpretation of these results is attempted on the basis of the difference in the degree of bound nitrille group pairs (bound through intermolecular dipole-dipole interactions) in the structure of PAN heat treated under the different conditions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070271103
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