Thermally initiated product chemistry in TNT: molecular beam approach
Abstract
Though they have not traditionally been used in this manner, cold molecular beam methods, enabling soft laser ionization time-of-flight mass spectrometry (TOFMS), provide good potential for directly following evolving products in systems that may display complex product chemistry, even down to µs timescales. No such direct observations have been made on energetic systems (explosives). There are particular opportunities for new experiments of these kinds involving energetic materials. Theoretical studies in recent years have made definite predictions concerning initiating chemistry and key early intermediates in energetic systems, predictions that appear to be testable in new experiments. The purpose of this Short Term Innovative Research (STIR) project is to explore some of these predictions. Initial experiments will be carried out on TNT, for several reasons. TNT stands out as a system where a number of clear and interesting theoretical predictions concerning detonation chemistry have been made in recent years, predictions that appear to be testable by the methods outlined herein. Furthermore, TNT, aside from being a ubiquitous explosive, also happens to be a stable and safe material to work with. For the foregoing reasons, it is an ideal system for the proof-of-concept experiments proposed. Experiments will study the evolution of products following thermal impulses. Thermal impulses will be produced by laser pulse heating of metal rod surfaces on which solid films of TNT have been deposited; the mean surface temperatures can be varied by varying the laser pulse fluences. For a given surface temperature, the ensuing products will be entrained in a rare gas flow that undergoes supersonic expansion, after which the center stream is skimmed to form a molecular beam. Thereafter, TOFMS will be carried out to identify products. Experiments involving thin film depositions of energetic materials on metal rods should be practical and safe for later extension to a variety of different systems. In addition, some initial experiments will be carried out on the decomposition chemistry of TNT clusters, since clusters of increasing size increasingly resemble condensed phase. If these experiments are successful, more sophisticated cluster experiments can be carried out in the future.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810052
Entities
People
- Mark Sulkes
Organizations
- Army Contracting Command
- Tulane University of Louisiana
- United States Army