Unraveling shock-induced chemistry using ultrafast lasers
- Los Alamos National Laboratory
The exquisite time synchronicity between shock and diagnostics needed to unravel chemical events occurring in picoseconds has been achieved using a shaped ultrafast laser pulse to both drive the shocks and interrogate the sample via a multiplicity of optical diagnostics. The shaped laser drive pulse can produce well-controlled shock states of sub-ns duration with sub-10 ps risetimes, sufficient for investigation offast reactions or phase transformations in a thin layer with picosecond time resolution. The shock state is characterized using ultrafast dynamic ellipsometry (UDE) in either planar or Gaussian spatial geometries, the latter allowing measurements of the equation of state of materials at a range of stresses in a single laser pulse. Time-resolved processes in materials are being interrogated using UDE, ultrafast infrared absorption, ultrafast UV/visible absorption, and femtosecond stimulated Raman spectroscopy. Using these tools we showed that chemistry in an energetic thin film starts only after an induction time of a few tens of ps, an observation that allows differentiation between proposed shock-induced reaction mechanisms. These tools are presently being applied to a variety of energetic and reactive sample systems, from nitromethane and carbon disulfide, to microengineered interfaces in tunable energetic mixtures. Recent results will be presented, and future trends outlined.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC52-06NA25396
- OSTI ID:
- 1043551
- Report Number(s):
- LA-UR-10-08059; LA-UR-10-8059; TRN: US201214%%92
- Resource Relation:
- Conference: Pacifichem 2010 ; December 15, 2010 ; Honolulu, Hi
- Country of Publication:
- United States
- Language:
- English
Similar Records
Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development.
LLE Review Quarterly Report (January-March 2001). Volume 86