ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    A Laser-Induced Fluorescence Study of OH Desorption from Pt in H2O/O2 and H2O/H2 Mixtures (1994)
    s.l. : American Chemical Society
    Langmuir 10 (1994), S. 699-708 
    Details
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/la00015a018
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Calculations of the ionization thresholds and electron affinities of the neutral, positively and negatively charged C60—"follene-60'' (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 2525-2526 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ionization thresholds and electron affinities are calculated within the local density approximation for the neutral, positively and negatively charged clusters of C60. The evaluated energies are found to be in good agreement with available experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455947
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    A laser-induced fluorescence study of OH desorption from Pt(111) during oxidation of hydrogen in O2 and decomposition of water (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 5827-5835 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The desorption of OH radicals from Pt(111) at high temperature, (approximately-greater-than)1000 K, during the water formation (H2+1/2 O2→H2O) and water decomposition reactions, respectively, was investigated using the laser-induced fluorescence technique. The results are compared with corresponding data from our laboratory for polycrystalline Pt. The OH desorption rate in H2+O2 at 1–100 mTorr total pressure has its maximum at 8%–9% relative H2 concentration for surface temperatures between 1100 and 1400 K. With H2 replaced by D2, the OD desorption rate maximizes at somewhat higher relative hydrogen content. The apparent activation energy for OH desorption increases from about 1.4 eV at low relative hydrogen concentration to about 2.0 eV at hydrogen contents of 25% or more. For the water decomposition reaction, the apparent activation energy for OH desorption was found to be 1.7±0.2 eV at 0.5 Torr and 1.9±0.2 eV at 1 Torr. These differences in apparent activation energies are primarily due to kinetic effects. The results are analyzed within a kinetic model previously developed by Hellsing et al. [J. Catal. 132, 210 (1991)], and are also compared with previous data for polycrystalline Pt. The kinetic model calculations give good overall agreement with the measured OH desorption rates as functions of temperature, H2/O2 mixture and H2O pressure, respectively. A nonuniqueness problem, with respect to the choice of kinetic parameters, is encountered in the simulation of the measured data; quite different sets of two of the kinetic constants, namely the activation energy for water formation (via OH+H→H2O) and the activation energy for OH desorption can reproduce the data as long as their difference is constant.This nonuniqueness problem, which is a consequence of the steady-state nature of the measurements, is analyzed and discussed in some detail, as are some apparent contradictions in the absolute values of reported kinetic constants in the literature. From this analysis two important conclusions are drawn. (i) The apparent contradictions in the literature about absolute values of activation energies for the water formation reaction and for OH-desorption may be less severe than believed or nonexistent. (ii) Coverage dependent activation energies must be considered and experimental exploration of such coverage dependencies are needed to create a firmer base for the kinetic modeling of the H2/O2 reaction on Pt. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469315
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    First-principle calculations of the ionization potentials and electron affinities of the spheroidal molecules carbon (C60) and lanthanum carbude (LaC60) (1988)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 110 (1988), S. 8701-8703 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00234a024
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of hydroxyl desorption rates from platinum using spatially resolved imaging of laser-induced fluorescence (1993)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 97 (1993), S. 12828-12834 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100151a032
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Statistical theory of cluster cooling in rare gas. I. Energy transfer analysis for palladium clusters in helium (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 9848-9858 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The cooling and heating of palladium clusters Pd13 and Pd55 by binary collisions with atoms of a surrounding helium gas are studied by means of molecular dynamics simulation. The efficiency of the collisional energy transfer is determined as a function of cluster and gas temperature and of cluster phase, the cluster being in either a solid or a liquid phase. A simple statistical analysis is presented for the energy transfer between a cluster and a rare gas atom. The analysis is based on an ergodic collision assumption of microcanonical relaxation in each collision. The deviation from this limiting law is collected in a collision efficiency factor which reflects incomplete energy redistribution during the lifetime of the collision complex. The thermal energy and change in heat capacity observed for the clusters at the freezing (melting) transition is accounted for by a parametrized density of states reflecting separate contributions from a solid and a molten structure. The same density of states is then used in the ergodic collision theory for the analysis of energy transfer. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.477654
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Geometric and electronic properties of small vanadium clusters: A density functional study (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 10620-10625 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The geometric and electronic properties of vanadium clusters in the range from V2 to V8 have been investigated using the density functional theory, and an LCAO approach for the expansion of the electronic wavefunctions. The optimized low energy isomers are found to be three dimensional for clusters larger than the tetramer, and the evaluated bond dissociation energies, ionization potentials and electron affinities are in good agreement with experimental results. All cluster sizes are found to possess low magnetic moments as ground states, which is in contrast with previous suggestions. In the case of V3− and V4−, a comparison with photo-electron spectra is done by computing the self consistent excitation spectra. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474177
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Vanadium clusters: Reactivity with CO, NO, O2, D2, and N2 (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 2629-2636 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have investigated the size-dependent reactivity of vanadium clusters, V10–V60, with CO, NO, O2, D2, and N2 by using a laser-vaporization source, low-pressure reaction cell and photoionization time-of-flight mass spectrometer. The reaction probability in a collision between a cluster and a gas molecule was determined for each gas for the first and second molecule. The reactivity was measured at two different cluster-source temperatures: room temperature (RT) and liquid-nitrogen temperature (LNT). We find that vanadium clusters react readily with all molecules investigated. With CO, NO, and O2, the reaction probability is high and exhibits relatively weak size dependence. With D2 and N2, the overall reaction probability is lower, and significant size variations are observed over the whole size range investigated, with coinciding minima and maxima for the two molecules. Upon cooling of the cluster source to LNT, the reactivity increases, but the overall size dependence is very similar to that observed at RT. The reaction probability with the second molecule, S2, is lower than that with the first one, S1, for all gases investigated, and, in most cases, the size dependence in S1 and S2 is similar. By analyzing the total relative abundance of each cluster size as a function of reaction-cell pressure, we find that reaction of Vn with CO, NO, and O2 results in size-dependent cluster-product fragmentation of clusters in the size range n(approximate)10–20, most likely by metal-atom loss. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.477984
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    N2 on tungsten clusters: Molecular and dissociative adsorption (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 3232-3239 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have studied the size-dependent reactivity of W10–W60 with N2 under single-collision-like conditions by using a laser-vaporization source, a low-pressure reaction cell and a laser-ionization time-of-flight mass spectrometer. The reaction probability with the first and second N2 molecule was measured at two different cluster-source temperatures: room temperature (RT) and liquid-nitrogen temperature (LNT). For the RT clusters, a strong size dependence in the reaction probability was observed in the size range ∼10–26 atoms, with distinct local maxima at W16, W22, and W23. Upon cooling of the cluster source, the reaction probability increased significantly overall, and the relative variations with size decreased, but persisted. To get an indication of the bond strength of N2 on Wn, we heated the cluster products after reaction through irradiation with 4.02 eV photons from a XeCl excimer laser and checked for consequent desorption of adsorbate atoms or molecules. For the LNT clusters, heating with laser light caused a substantial decrease in the abundance of reaction products with nitrogen, whereas no significant change in the abundance of WnN2 was observed for the RT clusters. This indicates that a proportion of the N2 is relatively weakly bound to the LNT clusters, whereas on Wn produced at RT, only the strongly bound state/states of N2 exist. Based on comparisons with the N2-adsorption on W bulk surfaces, we conclude that the weakly and strongly bound states represent molecularly and dissociatively bound N2, respectively. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476913
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Basis-independent potential energy curves for the neutral diatomics of Li, Na and K evaluated by means of Hartree-Fock and different density functional potentials (1993)
    Springer
    Theoretical chemistry accounts 85 (1993), S. 249-254 
    Details
    ISSN: 1432-2234
    Keywords: Neutral diatomics ; Basis-independent potential energy curves ; Li2 ; Na2 ; K2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The solution of the Schrödinger equation for diatomic molecules when the finite element method is used gives the possibility to evaluate highly accurate basis-independent potential energy curves. In this work such types of numerically accurate potential energy curves on the HF level have been evaluated for Li2, Na2 and K2 and could be used as benchmarks in the optimization of basis sets. A comparison between recent LCAO HF calculations in which extended basis sets are used and the accurate values determined in this work show that there is a difference in total energy of 4×10−5 and 10−3 a.u. for Li, Li2, and Na, Na2, respectively. Evaluated dissociation energies are, however, due to the cancellation of numerical errors in much better agreement. Further, it is found that different exchange correlation potentials for the heavier molecules such as those given by von Barth-Hedin and Vosko, Wilk and Nusair reproduce experimental properties such as dissociation energies, vibrational frequencies almost as well as those achieved with advanced CI methods. TheXα potential gives accurate bond lengths for Na2 and K2, whereas the dissociation energies are too small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01129114
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...