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  • 2000-2004  (4)
  • 1980-1984  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Surface-induced dissociation of singly and multiply charged fullerene ions (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 5053-5057 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Collisions of singly and multiply charged ions C60z+ (z=1,2,3,4,5) with a hydrocarbon-covered stainless steel surface have been investigated; product ions of fragmentation and pickup reactions were determined as a function of the collision energy (100–500 eV) and the projectile charge z. All ions scattered off the surface are singly charged. The extent of fragmentation increases with the collision energy and the projectile charge. However, the increase of fragmentation with the charge of the projectile is less pronounced than expected from a full conversion of electronic energy, gained in the neutralization process, into internal energy of the ion. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1288032
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Isotope effects in the electron impact ionization of H2/D2, H2O/D2O, and C6H6/C6D6 near threshold (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 2456-2463 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Appearance energies of all parent ions and several fragment ions produced by electron impact ionization of the isotope systems H2/D2, H2O/D2O, and C6H6/C6D6 were determined with high precision using a dedicated high-resolution electron impact ionization mass spectrometer. The determination of the appearance energies from scans of the ion signal as a function of electron energy in the near-threshold region of each ion utilized a fitting and analysis procedure that has recently been successfully applied to the determination of appearance energies of singly and multiply charged rare-gas ions and several molecular ions and cluster ions. The experimentally determined appearance energies are in good agreement (i) with theoretical calculations that we carried out using standard quantum chemistry codes and (ii) with appearance energy values listed in standard reference data tables (to the extent that tabulated values are available). We find isotope shifts for all three systems ranging from a few meV for the parent ions to a few hundred meV for the fragment ions. The deuterated species always have the higher appearance energy. The present results for H2O/D2O and C6H6/C6D6 do not confirm the larger isotope effects that were reported earlier by Snegursky and Zavilopulo [Nucl. Instrum. Meth. Phys. Res. B 126, 301 (1997)]. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1428341
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Ionization energy studies for ozone and OClO monomers and dimers (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 984-992 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Electron impact ionization cross sections measured close to threshold are reported for both the monomers and dimers of ozone and OClO using a new high resolution electron impact apparatus. The present appearance energies AE(O3+/O3)=12.70±0.02 eV, AE (OClO+/OClO)=10.55±0.02 and AE(ClO+/OClO=13.37±0.03 eV derived from the measured ionization cross sections are in excellent agreement with the vertical threshold values determined for these ions by high resolution PES and PIMS photoionization studies. The corresponding appearance energies determined for the dimer ions, 10.10±0.3 eV for (O3)2+ and 9.87±0.2 eV for (OClO)2+, are both red shifted with respect to the monomer case. The bond energy (0.70–0.3+0.5) eV of (OClO)2+ estimated from these data is similar to that of other dimer ions, whereas the bond energy of (O3–O3+) with (2.55−0.4+0.6) eV is rather large suggesting an unusual structure for the cationic ozone dimer ion. Based on quantum chemical calculations on various levels we are led to the conclusion that the ion produced by ionization of the ozone dimer is no longer a conventional dimer ion where the two monomer units are still present (as is the case for the OClO system), but rather an ion of form O2(centered ellipsis)O4+ or a twisted ring structure of (O6)+. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1386669
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  • 4
    Electronic Resource
    Electronic Resource
    Quantitative investigation of the kinetic energy release in metastable decay reactions of (O2)n=2–10+ ions: Evidence for a change in the metastable decay mechanism as a function of cluster size (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 7583-7588 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Using a high resolution two sector field mass spectrometer of reversed geometry we have measured metastable fractions and mass-analyzed ion kinetic energy peaks for metastable decay reactions involving monomer evaporation via (O2)n+*→(O2)n−1++O2. Both, average kinetic energy release 〈KER〉 data derived from the peak shapes and the time dependence of the metastable fractions show a characteristic dependence on cluster size indicating a change in the metastable fragmentation mechanism when going from the dimer to the dekamer ion. Moreover, the 〈KER〉 data contain information about the transition state temperature and thus one can use finite heat bath theory to calculate the binding energies of the decaying cluster ions. The results obtained are in fair agreement with (i) previous results based on gas phase ion equilibria measurements and with (ii) the corresponding bulk value. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1465414
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  • 5
    Electronic Resource
    Electronic Resource
    New gas phase inorganic ion cluster species and their atmospheric implications (1980)
    [s.l.] : Nature Publishing Group
    Nature 285 (1980), S. 392-393 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Arnold et al.2 reported unusual ion masses at altitudes between 37 and 56km based on rocket-borne mass spectrometric techniques. These ions, NPH (non-proton hydrates), are listed in Table 1. The original suggestion by Arnold et al2 that these might be protonated formaldehyde has been discounted3. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/285392a0
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  • 6
    Electronic Resource
    Electronic Resource
    Fission tracks in minerals: Annealing kinetics, track structure and age correction (1983)
    Springer
    Physics and chemistry of minerals 9 (1983), S. 197-204 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract It is shown that the annealing kinetics of fission tracks in apatite can be described by a sum of exponential decay functions. From an analysis of the temperature dependence of this annealing law it is concluded that the etchability of fission tracks is due to extended defects, i.e. systems of dislocation loops. The multiexponential annealing law is also applied to prove that the plateau correction method is basically correct, but rather as a method for determining a lower limit than the “true” fission track age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00311955
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  • 7
    Electronic Resource
    Electronic Resource
    Absolute partial and total electron ionization cross sections for CCl4 from threshold up to 180 eV (1984)
    Springer
    Plasma chemistry and plasma processing 4 (1984), S. 235-249 
    Details
    ISSN: 1572-8986
    Keywords: Ionization cross section ; electron impact ; mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Electron impact ionization of carbon tetrachloride was studied as a function of electron energy from threshold up to 180 eV. A double-focusing mass spectrometer system in combination with an improved electron impact ion source was used, alleviating the problems of ion extraction from the source and the transmission of the extracted ions through the mass spectrometer system. Absolute partial ionization cross sections for the occurrence of CCl 3 + , CCl 2 + , CCl+, Cl 2 + , Cl+, C+, CCl 3 2+ , and CCl 2 2+ have been determined. In addition, the total ionization cross-section function of CCl4 is reported and compared with theoretical predictions based on a classical binary encounter approximation. Using nth root extrapolation the following ionization energies of the doubly ionized fragment ions have been derived: AE(CCl 3 2+ )=30.4±0.3 eV; and AE (CCl 2 2+ )=31.8±0.3 eV. In accordance with theoretical predictions and previous results, no stable CCl 4 + has been detected, however, metastable dissociation processes CCl 4 + → CCl 3 + have been observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568978
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