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  • American Institute of Physics (AIP)  (18)
  • EDP Sciences  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Dynamics of the detonation products of lead azide. I. Hydrodynamics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 4693-4708 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The present paper is the first of a series reporting on a comprehensive study of the hydrodynamics, kinetics, and spectroscopy of the transient species formed following the detonation of lead azide (LA). The spatial and temporal behavior of the detonation products expanding into vacuum is obtained via high-speed framing photography, transmission of a HeNe laser beam, and chemiluminescence from excited Pb atoms. The photography reveals that following the initiation of LA the products form an expanding, bell-shaped cloud. The HeNe beam is attenuated when the cloud of products traverses its route. The attenuation starts 4–15 μs after initiation and depends on the height of the beam above the LA sample. The chemiluminescence consists of two components: the first, appearing 1–2 μs after initiation, is obtained from excited products formed by the detonation near the surface of the sample, while the second, starting 2–14 μs after initiation, originates from the expanding cloud of products.The intensity and the temporal behavior of the second component of chemiluminescence depend on the distance to a barrier placed above the LA sample. The cloud contains gaseous products and solid particles which propagate perpendicular to the LA surface with a maximum velocity of 4.48±0.10 km/s and 3.78±0.18 km/s, respectively. To reproduce the experimental results, two alternative hydrodynamic models are applied: Stanyukovich's model [K. P. Stanyukovich, Unsteady Motion of Continuous Media (Pergamon, London, 1960), pp. 498–501] for isentropic expansion and London and Rosen's model [R. A. London and M. D. Rosen, Phys. Fluids 29, 3813 (1986)] for exploding foil. The latter model is preferred and when incorporating Beer's law and Mie's theory [C. F. Bohren and D. R. Huffman, Absorption and Scattering of Light in Small Particles (Wiley, New York, 1983), p. 77] it reproduces very well both the temporal behavior of the second component of chemiluminescence and the attenuation of the HeNe beam and suggests that lead particles with radius of 0.05–0.15 μm are involved in the attenuation. The model also provides an estimate of the composition of the product cloud and of the density of the gaseous and solid species as a function of time and distance from the LA sample.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350660
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  • 2
    Electronic Resource
    Electronic Resource
    Dynamics of the detonation products of lead azide: III. Laser-induced hole burning and flow visualization (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 45-52 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The cloud of products formed following the detonation of lead azide (LA) contains solid particles. Utilizing a pulsed beam of a neodymium: yttrium aluminum garnet (Nd:YAG) laser, the particles are evaporated and hole burning through the opaque cloud is demonstrated. The characteristics of the hole and of the expanding cloud are monitored in real time by a HeNe beam, high-speed framing photography and emission of excited Pb atoms. The hole is carried with the cloud and propagates at a constant velocity of 0.5–2.8 km/s, depending on the time and location of burning and given by d(h)/t(h), where d(h) is the distance from the LA sample to the center of the Nd:YAG beam and t(h) is the time from detonation to hole burning. The reduction in the number and size of the particles is monitored by scanning electron microscopy of the deposits formed on a substrate following the detonation. The propagation of the Nd:YAG laser pulse through the cloud is numerically modeled and provides an estimate of the increase in the temperature and the decrease of the size of the particles as a result of the interaction with the laser beam.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355253
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamics of the detonation products of lead azide. II. Formation of charged particles (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2138-2144 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The formation and temporal behavior of charged particles ensuing from the detonation of lead azide (LA) is studied. An ion probe tailored for measurements in the hostile environment produced following the detonation is described. The positive ions (most probably singly ionized lead atoms) and the electrons, which are simultaneously collected on separate electrodes, are embedded in the outer half of the expanding product cloud resulting from the detonation. They show similar temporal behavior and their maximum velocity is ∼4.5 km/s. The density of each of them at a distance of 2.5 cm from the LA sample is 4.3×1011–1.3×1012 cm−3 for detonation of 5–15 mg of LA, respectively. From the hydrodynamics of the expanding cloud and the density of the electrons, their temperature is estimated to be in the range 2600–3000 K. The results of the measurements are discussed in view of the mechanisms believed to govern the expansion of the product cloud following the detonation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353140
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  • 4
    Electronic Resource
    Electronic Resource
    Direct observation of preferential bond fission by excitation of a vibrational fundamental: Photodissociation of HOD (0,0,1) (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 2146-2148 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The 193 nm photodissociation of individual rotational levels of HOD molecules excited with one quantum of O–H stretching vibrational energy is described. Stimulated Raman excitation and coherent anti-Stokes Raman scattering are used to prepare and detect, respectively, the (0,0,1) vibrationally excited HOD. The OD and OH fragments are detected by laser induced fluorescence. The photodissociation of the HOD (0,0,1) molecules yields at least three times more OD than OH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459040
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  • 5
    Electronic Resource
    Electronic Resource
    Mode-selective bond fission: Comparison between the photodissociation of HOD (0,0,1) and HOD (1,0,0) (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 3341-3346 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The 193 nm photodissociation of individual rotational levels of HOD molecules excited with one quantum of O–H or O–D stretching vibrational energy is described. Stimulated Raman excitation and coherent anti-Stokes Raman scattering are used to prepare and detect, respectively, the (0,0,1) (O–H stretch) or (1,0,0) (O–D stretch) vibrationally excited HOD. The OD and OH fragments are detected by laser-induced fluorescence. In the photodissociation of HOD (0,0,1), the yield of both fragments is enhanced [relative to HOD (0,0,0)], but the yield of OD is increased 2.5±0.5 times more than that of OH. In the photodissociation of HOD (1,0,0), no enhancement of the yield of the fragments is obtained. Our results show that even the very lowest possible level of vibrational excitation can be "leveraged'' to effect selective bond breaking. Also, these results demonstrate that bond cleavage does not necessarily occur on the weakened bond and they agree with theoretical calculations indicating that the yield of OD and OH fragments depends on the Franck–Condon overlap of the vibrational wave function with the repulsive surface of the upper state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460839
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  • 6
    Electronic Resource
    Electronic Resource
    Control of fragment alignment via photodissociation from different types of parent rotation (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 4218-4221 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The alignment of the OH fragment following dissociation of H2O (1,0,0) at 193 nm has been measured as a function of initially prepared parent rotations. The degree of alignment is almost perfect for an in-plane rotation, but is reduced markedly for a mixture of in- and out-of-plane rotations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466190
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  • 7
    Electronic Resource
    Electronic Resource
    Preferential excitation and enhanced emission of Pb atoms following detonation of lead azide (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 322-324 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Preferential excitation of the 3P°1 state of the lead atom and enhanced emission in the Pb(3P°1Pb(3P°1→1D2) transition at 722.9 nm have been observed following the detonation of lead azide, Pb(N3)2. The detonation is initiated by a short laser pulse and the products are expanded through a supersonic nozzle. It is suggested that the enhanced emission is due to preferential excitation of Pb(3P°1) via energy transfer from electronically excited N2 combined with the effect of self-trapping of the emission from 3P°1 to the 3P0,1,2 states. The implications to short-wavelength chemical lasers are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104674
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  • 8
    Electronic Resource
    Electronic Resource
    Multiple charge reaction cell for studies of primary explosives (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 132-134 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A reaction cell for the detonation of primary explosives is described. The cell is 250 mm in diameter and contains 30 samples, which can be initiated consecutively using a laser beam. A manually driven mechanism is used to locate each charge in its turn in a central firing position without having to break the vacuum. Eight 3-in. observation windows and four 0.25-in. feedthrough ports allow recording and analysis of the emission resulting from the detonation products. The design provides a means for protection against accidental explosion. The cell is currently being used for spectroscopic studies of the gaseous reaction products obtained from the detonation of lead azide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140597
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  • 9
    Electronic Resource
    Electronic Resource
    Laser-induced hole-burning and flow visualization in the cloud of products of detonated lead azide (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1281-1283 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Utilizing a pulsed beam of a Nd:YAG laser, hole burning through the opaque cloud of products formed following the detonation of lead azide is demonstrated. The characteristics of the hole and of the expanding cloud are monitored in real time by a HeNe beam and by high-speed framing photography. The hole is carried with the cloud and propagates at a constant velocity of 0.5–2.8 km/s, depending on the time and location of burning. The hole burning is a result of eliminating solid particles from the cloud. The application of a laser to burn a hole in the detonation products from a solid explosive is demonstrated for the first time. This technique may serve as a method for flow visualization in an aerosol medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107617
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  • 10
    Electronic Resource
    Electronic Resource
    Real time diagnostics of detonation products from lead azide using coherent anti-Stokes Raman scattering (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 3516-3518 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the first example that applies coherent anti-Stokes Raman scattering (CARS) to real time diagnostics of detonation products from a solid explosive. The supersonically expanding gaseous products, from the detonation of either lead azide pellets or powders, are studied, using broadband CARS. The density, and the rotational and vibrational temperatures of ground electronic state N2 molecules, N2(X), are monitored as a function of time at a fixed distance, 3.3 cm, from the azide surface. The rotational temperature is low, around 200–300 K, while the vibrational temperature is around 2000 K for delays of 8–12 μs, following the initiation of detonation. The density of N2(X), during this time interval, increases from ∼1×1017 to 1×1018 cm−3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105667
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