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Laser Ablation of FOX-7: Proposed Mechanism of Decomposition
Civiš, Martin ; Rychlovský, Petr (referee)
A novel high-energy explosive material, FOX-7 (1,1-diamino-2,2-dinitroethylene), was studied using a combination of laser-induced breakdown spectroscopy (LIBS) and selected ion flow tube mass spectrometry (SIFT-MS). The LIBS technique uses short laser pulses (an ArF excimer laser) as the energy source to convert small quantities of a sample into plasma and to induce the emission of its molecular fragments or atoms. SIFT-MS is a novel method for absolute quantification based on chemical ionization using three reagent ions, with the ability to determine concentrations of trace gases and vapors of volatile organic compounds in real time. SIFT-MS was used to study the release of NO, NO2, HCN, HONO, HCHO, CH3CH2OH, and C2H2 after laser ablation of the explosive compound FOX-7 in solid crystalline form. The radiation emitted after excitation was analyzed using a time-resolved UV-vis spectrometerwith an ICCDdetector.The electronic bands ofCN(388nm),OH(308.4 nm), andNO(237.1 nm) radicals and the atomic lines of C, N, and H were identified.
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Laser Ablation of FOX-7: Proposed Mechanism of Decomposition
Civiš, Martin ; Rychlovský, Petr (referee)
A novel high-energy explosive material, FOX-7 (1,1-diamino-2,2-dinitroethylene), was studied using a combination of laser-induced breakdown spectroscopy (LIBS) and selected ion flow tube mass spectrometry (SIFT-MS). The LIBS technique uses short laser pulses (an ArF excimer laser) as the energy source to convert small quantities of a sample into plasma and to induce the emission of its molecular fragments or atoms. SIFT-MS is a novel method for absolute quantification based on chemical ionization using three reagent ions, with the ability to determine concentrations of trace gases and vapors of volatile organic compounds in real time. SIFT-MS was used to study the release of NO, NO2, HCN, HONO, HCHO, CH3CH2OH, and C2H2 after laser ablation of the explosive compound FOX-7 in solid crystalline form. The radiation emitted after excitation was analyzed using a time-resolved UV-vis spectrometerwith an ICCDdetector.The electronic bands ofCN(388nm),OH(308.4 nm), andNO(237.1 nm) radicals and the atomic lines of C, N, and H were identified.
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Resuspension chamber as a tool for determination of resuspendable fraction of soil and street dust
Civiš, Martin ; Hovorka, Jan (advisor) ; Ždímal, Vladimír (referee) ; Střižík, Michal (referee)
A purpose-built cylindrical resuspension chamber (V=0.437 m3 , S=0.35 m2 , S/V=8.38) was used for the dispersion of samples of soil and various kinds of dust. The samples were studied from the point of view of the number and mass distribution of aerosol particles which could affect the concentration of atmospheric aerosol. The samples were taken from lignite, power plant flue ash and from overburden soil in the North Bohemian surface mine Nastup. The individual samples were pneumatically dispersed inside the chamber under defined temperature-humidity conditions (20řC and relative humidity (RH) 50 %). An APS (Aerodynamic Particle Sizer) processing provided us with average size distributions of particle mass and number. Lignite and flue ash probably have the greatest potential impact on the concentration of atmospheric aerosol in the studied locality. The amount of the resuspended mass of the samples varied between 0.001 % (overburden soil) and 0.32 % (mine road). The lignite and flue ash samples were then analyzed by gravimetric methods using the HI (Harvard Impactor) and the SCI (Sioutas Cascade Impactor). The flue ash contained higher amounts of fine particles than the lignite. Subsequent chemical analysis by electron microscope of the filters with deposits of power plant flue ash showed that the PM2.5...
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