Accession Number:

ADA387435

Title:

Detection of Energetic Materials by Laser Photofragmentation/Fragment Detection and Pyrolysis/Laser-Induced Fluorescence

Descriptive Note:

Final rept. Jan 1997-Dec 1999

Corporate Author:

ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD

Report Date:

2001-02-01

Pagination or Media Count:

39.0

Abstract:

Trace concentrations of energetic materials such as 2,4,6-trinitrotoluene TNT, pentaerythritol tetranitrate PETN, and hexahydro-l,3,5-tinnitro-s-triazine RDX are detected by laser photofragmentationlfragment detection PFFD spectrometry. In this technique, a single laser operating near 227 nm photofragments the parent molecule and facilitates the detection of the characteristic NO fragment by means of its A2lr-X2 II 0,0 transitions near 227 nm. Fragment detection is accomplished by resonance-enhanced multiphoton ionization REMPI with miniature electrodes and by laser-induced fluorescence LIF with a photodetector. Experiments are also conducted in the visible region using 453.85-nm radiation for photofragmentation and fragment detection. Sand samples contaminated with PETN and RDX are analyzed by a pyrolysisLIF technique, which involves pyrolysis of the energetic material with subsequent detection of the pyrolysis products NO and NO2 by LIF and PFLlF, respectively, near 227 nm. Applying these techniques to the trace analysis of TNT, PETN, and RDX at ambient pressure in room air is demonstrated with limits of detection SN 3 in the range of low parts-per-billion to parts-per-million for a 20-s integration time with l0-l20 micronj of laser energy at 226.8 nm and 5 mJ at 453.85 mm An increase in detection sensitivity is projected with an increase in laser energy and an improved system design. The analytical merits of these techniques are discussed and compared to other laser-based techniques.

Subject Categories:

  • Physical Chemistry
  • Lasers and Masers
  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE