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  • 11
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 2214-2221 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: A first-order model is developed for collisional activation as effected via resonance excitation and helium buffer gas in the Paul ion trap. For an ion population at steady-state under specified experimental conditions, the kinetic theory of ion transport in gases is first used to calculate an effective temperature shown to be identical to the internal temperature for molecular ions in an atomic gas. The evolution of the ion internal energy is then followed by a random walk simulation designed to be representative of the actual collisional energy transfer process, except ion losses due to dissociation and reactive processes during collisional activation are excluded. During the simulation, inelastic ion-neutral collisions increase the average ion internal energy via small energy changes (both positive and negative) until a steady-state condition is reached in which excitation and deexcitation processes are balanced. Histogramming the simulated data reveals a Boltzmann-type internal energy distribution whose average internal energy is the same as that calculated for a true Boltzmann distribution at the same internal temperature. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 6479-6489 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The reaction of CN with O2 has been studied through a photolysis-probe laser experiment in a cell at a total pressure of 70 mTorr. Rotationally hot CN reagent was prepared by 193 nm photolysis of BrCN. NCO(X˜ 2Π) product in various vibronic levels was detected by laser fluorescence excitation in its A˜ 2Σ+–X˜ 2Π band system at variable delays after the photolysis laser. In order to monitor the CN collisional relaxation which is taking place simultaneously with the reaction, we have also derived the CN rotational state distribution as a function of the photolysis-probe delay from laser fluorescence excitation spectra of the CN B 2Σ+–X 2Σ+ (0,0) band. From these observations, we deduce that rotationally hot CN reacts more slowly than thermalized CN. Moreover, reaction of the former yields NCO product with greater bending vibronic excitation. These results are compared with previous dynamical studies of this reaction, carried out with crossed beams and in cells. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
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  • 13
    ISSN: 1468-2494
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Dandruff is a common problem in approximately 30% of the world's population. Reports in the literature regarding treatment of this condition with various antidandruff shampoos usually report the level of active ingredient within the formulation. However, we propose that a more important parameter relating to antidandruff efficacy is the amount of active ingredient delivered to the scalp from the shampoo. This report describes the results from two studies designed to investigate the relationship between the level of zinc pyrithione (ZnPTO) deposited onto the scalp and the resultant scalp condition. A double-blind randomized vehicle-controlled clinical study comparing three shampoos – a vehicle, a low-depositing ZnPTO shampoo and a high-depositing ZnPTO shampoo – was carried out in the U.K. with 53 panelists with dandruff or mild-to-moderate seborrheic dermatitis of the scalp. Both shampoos containing ZnPTO were significantly superior in antidandruff efficacy to the vehicle. Furthermore, the high-depositing ZnPTO shampoo was significantly superior compared with the low-depositing ZnPTO shampoo in terms of both antidandruff efficacy and antimycotic activity. Antidandruff performance and antimycotic activity of ZnPTO-containing shampoos is highly dependent on the amount of active ingredient delivered to the scalp. Furthermore, careful manipulation of the formulation parameters of an antidandruff shampoo can result in enhanced levels of delivery of the active ingredient without having to increase the level of active ingredient within the formulation.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 4155-4162 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A compact (150 μm×150 μm), electrostatic actuator for out-of-plane (z) actuation of a probe tip has been designed, fabricated, and tested. Static deflections of ±0.7 μm out of the plane of the substrate have been achieved. The device consists of a single crystal silicon tip on a torsional cantilever with out-of-plane interdigitated electrode capacitors. This cantilever and electrode design allows a wide range of stiffnesses, actuator force, and frequency response. Significant improvements in performance (larger tip displacement and increased sense capacitance) and a higher density of devices per unit area can be obtained as the minimum feature size decreases. Applications such as information storage, molecular manipulation, and nanolithography require high density, parallel arrays for reasonable throughput. To demonstrate the suitability of this device for use in such arrays, a 12×12 array of microelectromechanical probe tips with integrated actuators and capacitive sensors for scanning probe microscopy has been fabricated. The size of each array element is about 150 μm by 150 μm with a tip-to-tip spacing in the array of 200 μm. Given these dimensions, the packing density of the devices is about 2500 units/cm2. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 3080-3084 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The hardware necessary for the electro-optic study of conducting polyelectrolyte solutions is frequently not commercially available or financially practical. The designs of an electrical rectangular pulse switch and polarity-reversing relay switch capable of producing 3 kV 5 A direct current pulses lasting longer than 100 μs are presented. As an example of the operation of this equipment, the electric birefringence of an aqueous solution of the Pseudomonas bacteriophage Pf1 in tris/EDTA buffer is presented. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4282-4288 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: In this study, we have utilized characterization methods to identify the nature of metal impurity precipitates in low performance regions of multicrystalline silicon solar cells. Specifically, we have utilized synchrotron-based x-ray fluorescence and x-ray absorption spectromicroscopy to study the elemental and chemical nature of these impurity precipitates, respectively. We have detected nanometer-scale precipitates of Fe, Cr, Ni, Cu, and Au in multicrystalline silicon materials from a variety of solar cell manufacturers. Additionally, we have obtained a direct correlation between the impurity precipitates and regions of low light-induced current, providing direct proof that metal impurities play a significant role in the performance of multicrystalline silicon solar cells. Furthermore, we have identified the chemical state of iron precipitates in the low-performance regions. These results indicate that the iron precipitates are in the form of oxide or silicate compound. These compounds are highly stable and cannot be removed with standard silicon processing, indicating remediation efforts via impurity removal need to be improved. Future improvements to multicrystalline silicon solar cell performance can be best obtained by inhibiting oxygen and metal impurity introduction as well as modifying thermal treatments during crystal growth to avoid oxide or silicate formation © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 17
    ISSN: 1520-5002
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Maschinenbau
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 8868-8875 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: We report on the hyperfine structure of N=1, J=3/2 levels of 62 NO2 vibronic states in the 16 850–21 500 cm−1 region, as determined via quantum beat spectroscopy. The hyperfine structure of these levels of mixed A˜ 2B2/X˜ 2A1 electronic character is dominated by the X˜ 2A1 Fermi-contact interaction, and a decrease in the hyperfine splittings with increasing energy is revealed when our results are compared with previous studies in the 11 200–13 700 cm−1 region. This comparison also reveals the loss of a correlation between band intensity and Fermi-contact constant. A detailed comparison of our results with theoretical predictions for the 16 600–18 700 cm−1 region is presented. We find that vibrational averaging of the X˜ 2A1 Fermi-contact interaction is reflected in the hyperfine interaction of bands in this region, and should also be a factor in producing the small hyperfine splittings observed at energies near dissociation threshold. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 525-531 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: The sign and magnitude of Landé gF factors for single NO2 rovibronic (J=3/2) eigenstates in the 15 cm−1 region below dissociation threshold (D0=25 128.57 cm−1) were investigated using Zeeman quantum-beat spectroscopy. The derived Landé gF factors exhibit pronounced fluctuations about an average much smaller than expected in the absence of rovibronic perturbations, which destroy the goodness of the N and K quantum numbers and the J=N+S coupling scheme. The F=J+I coupling scheme was found to be valid near D0 to within the uncertainty of our measurements, and the average Landé gF factors near dissociation threshold are in good agreement with those calculated under the assumption of complete rovibronic mixing. Our findings do not provide evidence for the participation of repulsive quartet states near dissociation threshold. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Inorganic chemistry 34 (1995), S. 5215-5219 
    ISSN: 1520-510X
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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