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  • 1
    Electronic Resource
    Electronic Resource
    Thiosulfuric acid analog of quinine as a potential antimalarial agent (1973)
    s.l. : American Chemical Society
    Journal of medicinal chemistry 16 (1973), S. 1042-1043 
    Details
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jm00267a019
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  • 2
    Electronic Resource
    Electronic Resource
    High-energy 4ω probe laser for laser-plasma experiments at Nova : Proceedings of the 12th topical conference on high temperature plasma diagnostics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1089-1092 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For the characterization of inertial confinement fusion plasmas, we implemented a high-energy 4ω probe laser at the Nova laser facility. A total energy of 〉50 J at 4ω, a focal spot size of order 100 μm, and a pointing accuracy of 100 μm was demonstrated for target shots. This laser provides intensities of up to 3×1014 W cm−2 and therefore fulfills high-power requirements for laser-plasma interaction experiments. The 4ω probe laser is now routinely used for Thomson scattering. Successful experiments were performed in gas-filled hohlraums at electron densities of ne〉2×1021 cm−3 which represents the highest density plasma so far being diagnosed with Thomson scattering. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149513
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  • 3
    Electronic Resource
    Electronic Resource
    A detailed study of the reactions between size selected aluminum cluster ions, Al+n (n=3–26), and oxygen (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 5728-5738 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A detailed study of the reactions between size selected aluminum cluster ions and oxygen is presented. The experiments were performed using a low energy ion beam apparatus. Measurements of product distributions and total reaction cross sections at collision energies of 1.2 and 4.2 eV for aluminum cluster ions with between 3 and 26 atoms are reported. The total reaction cross sections increase with cluster size in a way which roughly correlates with the increase in the cluster's physical size. The main products are Al+n−4, Al+n−5, Al+n−6, and Al+. Only a very small fraction of the product ions contain oxygen. We suggest that the reaction occurs by chemisorption of O2 onto the cluster followed by rapid loss of two Al2O molecules to give Al+n−4. If the Al+n−4 fragment contains sufficient energy it will undergo further dissociation by loss of one or more aluminum atoms to give Al+n−5, Al+n−6, and Al+. RRKM theory is used to estimate the amount of energy above the dissociation threshold required to cause dissociation of the bare clusters on the experimental time scale. For the larger clusters this excess energy is remarkably large. Using this data we are able to deduce some information about energy disposal in the reaction. It is likely that the Al2O molecules carry away a substantial fraction of the exothermicity arising from chemisorption of oxygen onto the clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453547
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  • 4
    Electronic Resource
    Electronic Resource
    Collision induced dissociation of aluminum cluster ions with chemisorbed oxygen, AlnO+m (n=3–26, m=1,2): Influence of electronic structure on stability (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 1610-1619 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The collision induced dissociation of size selected aluminum cluster ions with chemisorbed oxygen, AlnO+m (n=3–26, m=1,2) by argon has been studied using a low energy ion beam apparatus. The main product from AlnO+ is Al+n−2. Aln−2O+ and Al+n−4 are observed from AlnO+2. These products can be accounted for by loss of Al2O (which is very strongly bound) from the clusters. The experimental results were used to bracket the Aln/O interaction energies at 8.0±1.0 eV for Al+6 and 7.5±1.0 eV for Al+19. These large interaction energies indicate that oxygen is multiply bonded to the clusters. The collision induced dissociation cross sections show a strong cluster size dependence. Minima in the cross sections as a function of cluster size are ascribed to particularly stable clusters. The number of aluminum atoms in the particularly stable AlnO+m cluster increases with the addition of oxygen atoms. The stability of these clusters can be accounted for by the electronic shell model if it is assumed that binding oxygen atoms to the clusters removes electrons from the cluster orbitals so that more aluminum atoms are required to close the electronic shells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453221
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  • 5
    Electronic Resource
    Electronic Resource
    Collision induced dissociation of metal cluster ions: Bare aluminum clusters, Al+n (n=3–26) (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 3876-3885 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The collision-induced dissociation of aluminum clusters, Al+n (n=3–26), by argon, at a center of mass collision energy of 5.25 eV, has been studied using a low energy ion beam apparatus. Product branching ratios and collision induced dissociation cross sections are presented and discussed. The main product is Al+ for the smaller clusters and Al+n−1 for the larger ones. The cross sections rise to a peak at Al+6−Al+9 and then decrease with increasing cluster size. Cross sections for Al+7, Al+13, Al+14, and Al+23 are significantly smaller than their neighbors. A crude kinetic model is used to derive approximate cluster ionization potentials from the product branching ratios. The IPs initially rise with cluster size, peak at Al6 and then decrease. The IP of Al7 is particularly low and there is a sharp drop in IP at Al14 where the IP falls below that of the atom. The results suggest that the dissociation energies increase for the larger clusters and there is evidence that Al+7, Al13, Al+13, Al+14, and Al+23 have enhanced stability. The results are compared to the predictions of the electronic shell model which can account for some of the results but predicts additional features which are not observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451948
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  • 6
    Electronic Resource
    Electronic Resource
    The reactions of mass selected aluminum cluster ions, Al+n (n=4–25), with oxygen (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 5373-5375 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The reactions between aluminum cluster ions Al+n (n=4–25) with oxygen have been studied using a low energy ion beam apparatus at a center of mass collision energy of 1 eV. Some extraordinary reactions were observed. Oxygen very specifically cleaves the aluminum clusters, Al+n, resulting in Al+n−m cluster ions where m=4, 5 and for the larger clusters 10. Al+ is also an important product ion for clusters with n≤13. No oxygen containing product ions were observed. We suggest that addition of oxygen to the cluster raises the ionization potential and makes AlxO+ and AlxO+2 products energetically unfavorable, thus neutral oxide species are formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451157
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  • 7
    Electronic Resource
    Electronic Resource
    Mobilities of metal cluster ions: Aluminum and the electronic shell model (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 2399-2407 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The mobilities of size-selected aluminum cluster ions containing 5–73 atoms have been measured using injected ion drift tube techniques. The mobilities show an apparent correlation with the electronic shell model: Clusters close to the electronic shell closings have enhanced mobilities. A structural transition appears to be associated with the shell closing with 138 valence electrons. Structural isomers were identified for a few clusters at low temperatures. But with only one exception (Al45+) the annealing temperatures of these isomers are below room temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464167
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  • 8
    Electronic Resource
    Electronic Resource
    Mobilities of silicon cluster ions: The reactivity of silicon sausages and spheres (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 9180-9190 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The mobilities of size selected silicon cluster ions, Si+n (n=10–60), have been measured using injected ion drift tube techniques. Two families of isomers have been resolved by their different mobilities. From comparison of the measured mobilities with the predictions of a simple model, it appears that clusters larger than Si+10 follow a prolate growth sequence to give sausage-shaped geometries. A more spherical isomer appears for clusters with n〉23, and this isomer completely dominates for unannealed clusters with n〉35. Annealing converts the sausage-shaped isomer into the more spherical form for n〉30. Activation energies for this "sausage-to-sphere'' structural transition have been estimated for several cluster sizes and are ∼1.2–1.5 eV. We have examined the chemical reactivity of the sausages and spheres towards both C2H4 and O2. With C2H4 large differences in reactivity of the isomers were found, with the spherical isomer often being more reactive than the sausage form by more than an order of magnitude. With O2 the variations in reactivity were smaller. Despite the substantial differences in reactivity observed for the two isomers in the cluster size regime where both forms coexist, examination of a broader range of cluster sizes shows that there is not a systematic change in reactivity associated with the geometry change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462228
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  • 9
    Electronic Resource
    Electronic Resource
    Photodissociation kinetics of aluminum cluster ions: Determination of cluster dissociation energies (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 2912-2921 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photodissociation of aluminum clusters, Al+n (n=7–17), has been studied over a broad energy range (1.88–6.99 eV). Measurements of the lifetimes of the photoexcited clusters are described. Dissociation energies have been determined by comparing the measured lifetimes with the predictions of a simple RRKM model. The dissociation energies show an overall increase with cluster size, but there are substantial oscillations around n=7–8 and n=13–15. Cluster cohesive energies are derived from these results and from previous measurements of the dissociation energies of the smaller clusters. The cohesive energies of the larger clusters (n〉6) are in good agreement with the predictions of a simple model based on the bulk cohesive energy and the cluster surface energy. However, the cohesive energies are substantially larger than the results of recent ab initio calculations. The photodissociation spectrum of Al+8 has been measured and shows a broad absorption feature with a maximum ∼470 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456961
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  • 10
    Electronic Resource
    Electronic Resource
    Chemistry of semiconductor clusters: A study of the reactions of size selected Si+n (n=3–24) with C2H4 using selected ion drift tube techniques (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 3615-3628 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The chemical reactions of size selected Si+n (n=3–24) clusters with C2H4 have been studied at thermal energies using selected ion drift tube techniques. Except for Si+3 (which dehydrogenates C2H4 to yield Si3C2H+2) the dominant products arise from adsorption of C2H4 onto the silicon clusters. The reaction rates show large variations with cluster size. Si+13 and Si+14 were found to be particularly unreactive. The reactions were studied over a temperature range of 143–298 K. The reactivity increases as the temperature is lowered indicating that variation in the rates observed for the different cluster sizes is not due to an activation barrier, but reflects the stability of the SinC2H+4 adducts. Statistical phase space theory was used to model the reactions of Si+4–Si+10 and provide an estimate of the binding energy of the first C2H4 to these clusters. The binding energies vary between 0.8 and 2.0 eV. Binding energies of this magnitude are too small to be accounted for by strong di-σ bonding, suggesting that the C2H4 molecule is bound to the silicon clusters by a weaker π-bonding interaction. Kinetic evidence for the presence of structural isomers was found for several clusters. With Si+9 the relative abundance of an unreactive isomer could be changed from ∼1% up to 17% by changing the source conditions. More than one C2H4 molecule will adsorb onto the silicon clusters (up to eight adsorb on Si+4). Rate constants for the adsorption of the first few (up to seven) C2H4 molecules on Si+n (n=4–10) have been determined. They show large variations with the number of adsorbed C2H4 molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455820
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