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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 3620-3628 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Double-differential cross sections for the interaction of Na(3 2S) and Na(3 2P) with SF6 have been measured in crossed beam experiments for center of mass collision energies between 0.25 and 1.75 eV. In comparison with recently reported experiments the reaction with vibrationally excited SF6 is found to be more effective than the one with electronically excited Na. Results from an ab initio CASSCF calculation with Na in the ground state and the 3P state are presented. The experimental findings and the results from the calculation lead us to two different models for the reaction in the ground state and the excited state: While the well known harpooning model is verified for the ground state the reactive collisions with excited Na are mediated by nonadiabatic (nonreactive) transitions to the ground state surface. For these transitions the vibrational motion of SF6 is much more efficient than the relative motion in the collision. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 4807-4814 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Double differential cross sections of sodium in both the 3S ground state and the 3P electronically excited state scattered from SF6 and SiF4 have been measured at center of mass collision energies of 0.6 and 2.0 eV for SF6 and 1.0 eV for SiF4. For the experiments with Na(3P), a two frequency excitation scheme is applied, by which an excitation efficiency (determined by scattering experiments) of 31% is obtained. In the SF6 experiments, one finds a substantial transfer of the collision energy into the vibrational and rotational degrees of freedom of SF6. A transfer of electronic energy of Na(3P) into SF6 is not observed in nonreactive collisions. For the NaF formed in the reaction, an angular distribution originating from a long-lived complex, superimposed by a forward peak caused by a direct reaction mechanism is found. Especially the ground state measurements show an angular-dependent velocity distribution of the product. Compared to forward and backward scattering in sideways collisions, a lower velocity is found. From Na(3S) to Na(3P), the general characteristic does not change. The gain of reactivity with the excitation is decreasing with the collision energy. For the experiments with Na(3P) and SiF4, a quenching channel is found. The energy transferred to SiF4 is in good agreement with the prior distribution, calculated in a simplified RRHO model. The statistical behavior and the shape of the angular distribution of the intensity suggest the interpretation by the formation of a long-lived collisional complex. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Chemical Physics Letters 214 (1993), S. 34-38 
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 27 (1995), S. 1449-1455 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract To achieve a high return on investment, laser systems must be used to their fullest capacity, avoiding power losses and downtimes. High-quality laser gases are therefore needed to run the laser. But if the quality of the gas cannot be guaranteed all the way from the cylinder to the laser cavity, the risk of impurities such as water vapour and hydrocarbons or particles being entrained into the laser system is large. Unstable laser operation and damage to the resonator optics can result, needing costly repairs. The profitability of laser operations is also affected by the selection of the assist gas. High-purity oxygen, for example, results in a correspondingly high cutting speed in mild steel. In cutting stainless steel, on the other hand, any oxidation of the cut surface must be avoided in order to preserve the corrosion resistance. In contrast, different assist gases are used for laser welding depending on the wavelength of the laser radiation, the material or the energy per unit length of weld. Helium is often the most convenient choice for CO2 laser welding of mild steel and helium-argon mixtures for aluminium; argon is suitable for Nd:YAG laser weiding and productivity is increased by small additions of oxygen. Consequently, high-purity gases and suitable gas distribution equipment are the basis for a satisfactory return on investment.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0649
    Keywords: 32.30.Jc ; 32.50. + d ; 35.10.Fk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Laser-Induced Fluorescence Line Narrowing (LIFLN) measurements of hyperfine structure splittings performed on the cobalt I transition sequence3d 84s a 2 P 1/2→3d 74s4p z 24D 3/2 0 →3d 84s b 4 F 3/2are presented. The hyperfine coupling constants of theb 4 F 3/2 level were determined to beA = 302.8(1.9) MHz andB = − 81.6(18.2) MHz and are compared with results of both experimental and theoretical studies reported by other authors.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 16 (1928), S. 1045-1045 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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