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4 Chemical Characteristics of Bombs
Pages 56-70

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From page 56...
... , or within an ionic solid, such as ammonium nitrate, when mixed with fuel oil. Mixtures of high explosives are frequently used.
From page 57...
... , which employs electron attachment to neutral explosive molecules, succeeds. The light elements carbon and hydrogen usually serve as the reducing components of HE formulations.
From page 58...
... 58 O + N 94.98 68.26 81.06 81.68 85.21 59.57 82.18 94.29 82.28 82.57 73.37 81.91 79.98 81.06 78.45 67.22 82.94 68.97 Sum O % 59.97 45.5 43.22 51.58 39.32 46.11 43.82 50.09 63.69 52.14 59.23 63.41 36.9 43.22 60.73 48.88 8.5 44.58 wt a N % 35.01 22.76 37.84 30.1 45.89 13.46 38.36 44.2 18.59 30.43 14.14 18.5 43.08 37.84 17.72 18.34 74.44 24.39 wt H % Compositions 5.04 2.46 2.72 5.42 4.95 5.81 1.38 5.3 1.78 4.38 2.37 2.22 1.55 2.72 2.55 1.32 4.29 1.76 wt Their C % 0 29.28 16.22 12.91 9.84 and 34.62 16.45 15.94 13.05 24.24 15.87 18.47 16.22 19 31.46 12.77 29.28 wt Explosives 6 6 12 7 6 18 11 9 3 8 12 7 8 3 O O O 3 O O O 3 O O O O O O O O 4 6 4 O 2 12 3 6 O 3 3 4 8 4 3 10 5 O O 2 N N N 4 N 2 High N N N N N N N N N N 6 6 10 N 12 6 3 8 N 7 5 2 8 8 3 8 5 N 6 N 4 4 H H H H H H H H H H H H H H 6 3 2 6 6 5 6 6 3 2 4 5 6 2 7 Formula H C C C CH C C H C CH C C C C C C C C Common (HMTD) diamine D)
From page 59...
... 59 and Fire 64.77 60.76 87.39 69.74 79.15 55.75 71.01 86.14 76.95 ±8.47 95/56 66.39 39.72 43.2 46 53.7 49.80 ±8.19 for Group 45.05 42.26 28.72 37.19 49.98 38.78 44.84 52 46.14 ±8.01 63/9 54.47 30.75 43.2 35.6 37.35 40.27 ±6.85 Working Technical 19.72 18.5 58.67 32.55 29.17 16.97 26.17 34.14 30.81 ±11.01 58/13 11.92 8.97 0 10.4 16.35 11.91 ±2.23 The TWGFEX: 1.42 2.22 5.43 2.34 2.1 0.81 0.94 4.09 2.98 ±1.38 3.43 0.65 8.16 0 7.06 5/0.8 see 33.82 37.02 7.19 27.92 18.76 29.11 28.05 9.76 20.29 ±8.15 37/0 0 15.39 48.64 10 investigations, 8 forensic 6 O Pb 4 6 6 O in O O 3 6 6 3 6 O O O 4 9 O 3 3 O O Cl 6 7 6 4 4 3 4 3 CuN N N N N ClN N N O 2 3 5 N 9 6 4 2 2 N 3 18 H H H H H H 5 NO H H Cl 6 7 6 3 6 5 4 6 9 24 C C CH C C C C CH H C C H important considered (TAGN) explosives (TATB)
From page 60...
... Indeed, it has been stated, "A measurement of the oxygen and nitrogen densities, to an uncertainty of ±20%, gives a unique separation of explosives from other compounds."4 Note, however, that this analysis will fail for certain explosives that do not contain nitrogen, for example TATP. While analysis such as this is not useful for energetic materials such as TATP, it may be quite useful for more "common" explosive materials such as ammonium nitrate/fuel oil, or black and smokeless powders.
From page 61...
... As terrorists and other potential bombers become more sophisticated, both in their choice of explosive materials and in the way these materials are procured, transported, and concealed, detection methods must be changed concomitantly. For example, in the near term, a new class of energetic materials, ionic liquids (e.g., 4-diamino-1,2,4-triazolium dinitroamide [(NH2TazN(NO2)
From page 62...
... . Vapors that are emitted from a bomb may be present at concentrations two to four orders of magnitude less than the equilibrium vapor pressures shown in the figure, both because of enclosure in a bomb package and because explosive compositions containing other compounds may have lower vapor pressures than those shown for the pure explosive compounds.
From page 63...
... Another variable to consider is the tendency of high explosives to adsorb strongly on surfaces. It is well known in land mine detection studies that both dogs and chemical sensors show improved performance when soil moisture content is high.11 Water competes with TNT and DNT for binding on soil particles, thereby releasing more TNT and DNT into the soil airspace where these molecules can diffuse out for improved detection.
From page 64...
... The photonuclear reaction employs resonant gamma-ray absorption to produce an unstable nucleus that is subject to radioactive decay. This is another method that has been applied to determining elemental nitrogen content.16 Core electron ionization and subsequent characteristic X-ray emission gives rise to another broad class of methods, which might potentially be used for atom identification.
From page 65...
... Ultrasensitive detection approaches would be problematic in explosive-rich military environments and could also lead to false alarms due to the presence of chemical interferents. Some techniques applied for the identification of explosive molecules in the vapor phase include UV-Vis, infrared, and microwave absorption.
From page 66...
... The chief ion method currently used is IMS, which employs an electron source at ambient pressures to create negative ions of explosive vapors and characterize them by their drift times in a fixed electric field. It is not as selective as GC-MS, but it has been widely deployed for several reasons, including relatively low cost and simplicity of instrumentation.
From page 67...
... The rate of false positives from a simple density determination could be improved by additional elemental or molecular information. Nuclear quadrupole resonance (NQR)
From page 68...
... Raman microspectroscopy using fiber-optic techniques has been employed to determine characteristic vibrational spectral features, which can be used to identify explosives particles or surfaces contaminated with explosives.27 In one common application of IMS, a probe with an affinity for explosive particulates is rubbed on potentially contaminated luggage or shoe surfaces. Heating the probe to about 200oC in the IMS inlet vaporizes low-volatility solid explosives, such as RDX, for detection.
From page 69...
... Proceedings of SPIE-The International Society for Optical Engineering. Detection and Remediation Technologies for Mines and Minelike Targets II 1997, 671679.
From page 70...
... Pt. 1 Detection and Remediation Technologies for Mines and Minelike Targets VII 2002, 474-481.


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