Home | My Profile | Contact Us
Research Trends Products  |   order gateway  |   author gateway  |   editor gateway  
ID:
Password:
Register | Forgot Password

Author Resources
 Author Gateway
 Article submission guidelines

Editor Resources
 Editor/Referee Gateway

Agents/Distributors
 Regional Subscription Agents/Distributors
 
Trends in Applied Spectroscopy   Volumes    Volume 2 
Abstract
Vibrational spectroscopy and trace detection of explosive materials
D. O. Henderson, Y. S. Tung, R. Mu, A. Ueda, W. Curby, A. Mercado, Xi Li
Pages: 139 - 165
Number of pages: 27
Trends in Applied Spectroscopy
Volume 2 

Copyright © 1998 Research Trends. All rights reserved

ABSTRACT
 
The infrared spectra and some results from Raman scattering studies of explosive materials are presented in this review. Various sampling techniques for obtaining the infrared spectra of explosives adsorbed on high area metal oxide powders, explosives diffused into polymers and in the solid and liquid states are presented. The spectra obtained from various sampling methods are discussed in terms of the fundamental properties of explosives and detection technology. Other optical techniques such as ellipsometry for characterizing the sublimation rates of explosive thin films adsorbed on substrates are presented and are compared to the results obtained by atomic force microscopy. Assignments are proposed for the absorption lines observed in the spectra based on a group frequency analysis. The tabulated frequency data support the contention that infrared and Raman signatures can be applied to uniquely identify explosives. Diffuse reflectance infrared spectra of explosive vapors adsorbed on various substrates that may be potential collector materials are also discussed. ZnO, Al2O3, and TiO2 high area metal oxide powders are evaluated as potential collector materials by this technique and details are given for ethyleneglycol dinitrate (EGDN) adsorbed on these surfaces. The results indicate that Al2O3 and TiO2 adsorb (25°C) and desorb (40°C) EGDN without any decomposition, whereas decomposition products are observed for EGDN on ZnO when desorption is carried out at 40°C. The application of the attenuated total reflectance technique to monitor the diffusion of an explosive in a polymer is presented as well. A diffusion constant of 10-7 cm2/sec and an activation energy of 30-35 kJ/mol are determined for 2,4,6-trinitroluence diffusion in acrylonitrile-butadience rubber. Ellipsometric and atomic force microscopy (AFM) measurements of explosive thin films absorbed on Muscovite mica, a thermal oxide layer on silicon (hereafter referred to as silica) and highly ordered pyrolytic graphite are used to monitor the sublimation rates of explosives. A nonlinear sublimation rate is observed for 2,4,6-trinitrotoluene (TNT) adsorbed on Muscovite mica and silica. A first principles model is developed to account for the nonlinear sublimation rates observed for the explosive thin films. The model contains three parameters: 1) the interfacial interaction potential between the explosive and the substrate, 2) a critical decay length, and 3) the sublimation rate. Fitting the model to experimental data for TNT adsorbed on silica gave an interfacial interaction potential of ~57 kJ/mol, a critical decay length of ~1 nm and a sublimation constant of ~2.7 nm/hr. Similar parameters were obtained for TNT adsorbed on Muscovite mica. However, the data for TNT on the graphite substrate did not clearly exhibit nonlinear sublimation. This is interpreted as arising from a very weak interfacial potential between the TNT and the graphite surface, while the similarity of the parameters obtained for silica and Muscovite mica are attributed to the fact that both surfaces are terminated by SiO4 tetrahedra.
Buy this Article


 
search


E-Commerce
Buy this article
Buy this volume
Subscribe to this title
Shopping Cart

Quick Links
Login
Search Products
Browse in Alphabetical Order : Journals
Series/Books
Browse by Subject Classification : Journals
Series/Books

Miscellaneous
Ordering Information Ordering Information
Downloadable forms Downloadable Forms