Time and space resolved spectroscopy of nanoenergetic materials Dana Dlott Hyunung Yu Selezion A. Hambir School of Chemical Sciences and Fredrick Seitz Materials Research Laboratory University of Illinois at Urbana-Champaign
Outline of Effort Experimental measurements of engineered nanoenergetic materials dynamic response to heat and shock Response of isolated nanoparticles Interactions among nanoparticles Reaction propagation over short distances (100 nm to 1 mm)
Program Structure and Interactions Synthesis & Assembly PSU UIUC nano - macro Theoretical Modeling & Simulation USC PSU macro - nano NEEM Experimental Characterization & Diagnostics nano - macro UIUC PSU
Interactions with MURI team Experimental measurements of engineered nanoenergetic materials dynamic response to heat and shock Theoretical modeling and simulation: Test and verify simulations, suggest focus areas Synthesis and assembly: Performance testing of novel materials, suggestions for advanced materials PSU Experimental characterization and diagnostics: Microperformance testing of practical materials, suggestions to improve performance based on micro measurements
transparent polymer oxidizer 100 ps oxidizer 100 nm pulse 100 ps heating pulse is matched to metal particle thermal conduction. Particle is uniformly heat- ed, surroundings cold High repetition rate laser flash- heating (100/s) 40 mg sample (3 µm thick). Each shot 50 ng (150 µm diam). 10 5 shots per sample 10 cm 1 mm
Picosecond CARS measurements of flash heated materials fixed delay attenuator variable delay SPS CARS pulses 100 ps heating pulse thin film narrow band CD dye laser XY spectrograph CCD 1. Heat pulse 1053 nm, 100 ps, 0-500 µj energy 70 µm radius 2. Probe pulses visible, 10 µj 30 ps, 30 µm rad CD broad band CD dye laser YLF QS ML SHG 3. repetition rate = 80 per second
Picosecond laser system for flash- heating studies
Nitrate group consumption in Alex/NC 1.0 0.8 0.6 0.4 0.2 ONO2 survival fraction 800 CARS of NC -ONO 2 1200 1600 CARS wavenumber (cm -1 ) 0.0 J = 5.9 J/cm 2-1 0 1 2 3 4 5 delay time (ns) 0.2% 0.5% 1.0% 2.0% abrupt abrupt transition transition when when reactions reactions coalsece coalsece ~300 ps conc. indep CARS intensity (arb)
Energy release via time-resolved emission intensity (arb) Al atoms AlO 1% in NC 5.6 J/cm 2 3.9 J/cm 2 1.8 J/cm 2 0.4 J/cm 2 2ns 1% in NC 5.6 J/cm 2 3.9 J/cm 2 1.8 J/cm 2 0.4 J/cm 2 several ns 400 500 600 700 800 wavelength (nm) 0 10 20 30 time (ns) Energy release ~2 ns at low concentration Slows down at higher fluence as reaction propagates over greater distances
d avg Average distance d avg between nanoparticles is a ruler average distance d avg (nm) 3 m ρ ox Al 1500 1000 500 w m Al ρ ox Al = mass of Al in a nanoparticle ox = oxidizer density w = wgt fraction of nanoparticles 110nm 62nm NC/Al Teflon/Al 30nm 0 0 1 2 3 4 5 Al concentration (wgt%)
Reaction distance for 7 Al particles in Teflon mean distancce (nm) 2500 2000 1500 1000 500 215 100 60 30 30 (1.7) nm 30 (2.8) nm 60 (2.5) nm 62 (6.0) nm 101 (2.8) nm 111 (5.6) nm 215 (18) nm 0 0.0 2x10 11 4x10 11 energy per unit volume Al (J/m 3 )
Longer distance and directional propagation sample glass substrate thickness 1 µm to 100 µm near-ir flash heating pulse streakscope
Ultrafast (sub ns) microscopy of laser-initiated materials delay generator computer & video frame grabber CCD camera solid-state near-ir laser PS S N 2 - laser dye laser optical fiber
Energetic laser-triggered materials for computer-to to-plate imaging 2 µs duration laser pulse PDMS (silicone rubber) 2.5 µm substrate EM substrate
Femtosecond IR laser laser table 5W 532 fs osc 20W YLF 3 mj, 1kHz, 100 fs Titan amplifier pulse shaper PC shape control flash-heating/ IR transient absorption table shock pulse PC λ control IR OPA 4 pass amplifier 15W YLF IR probe IR ref spectrograph +IR array optical delay line spectrograph +CCD SFG SFG/shock table flip-in mirrors Fabry-Perot ètalons BB-IR NB-vis shock target array sample on motorized flashheating positioner pulse
Femtosecond IR laser (2.5-18 µm) C-H, C-C, Al-O, Al-F, C-F, O-H, etc.
Time-resolved IR (2.5-18 µm) signal BBIR Mirror beamsplitter reference dichroic beamsplitter spectrograph with IRFPA near-ir flash heating pulse signal
Shock spectroscopy of self- assembled monolayers on Au tethered ODT layer Ni Cr Au -CH 3 One 200 µm m x 200 µm element of a 50 mm x 50 mm array ~50,000 shots/array laser shock pulse glass substrate plasma contact liquid CaF 2 window SFG IR vis each SFG spectrum a few hundred shots
Properties of femtosecond laser- driven shock wave Pressure 5-10 GPa Material velocity ~0.8 km/s Shock velocity ~4 km/s (40Å/ps) Compression factor V = 0.2 Rise time 2-3 ps Fall time 15 ps
Shock data on 3 transitions of PDT (15 carbons) relative SFG signal I/I 0 1 0.8 0.6 0.4 0.2 0 <4 ps rise ~15 ps fall 15-carbon chain ν s ν as ν FR 0 50 100 150 200 250 300 delay time (ps) completely elastic recovery
Shock data on 3 transitions of 1 0.8 0.6 0.4 0.2 0 ODT/Au (18 carbons) <4 ps rise ~15 ps fall relative SFG signal I/I 0 shock ~30 ps decay sym asym bend 0 50 100 150 200 250 300 delay time (ps) viscoelastic compression
Model for viscoelastic compression of ODT θ = 23 θ = 85 θ = 85 θ = 12 Shock creates a mixture of single ( gt) and double g+g defects with high tilt angles that kill the SFG signal. tt -g t -g +g t +g 1% 10% 28% 5% V When shock unloads, the barriers are too high for either to relax to tt. However g+g can relax to upright t+g
Status of effort Status of effort Tools developed to study isolated nanoparticles and nanoscale propagation Ultrafast microscope upgrade completed Fast IR constructed, waiting for IR detector upgrade (Nov) Reaction propagation experiment constructed, waiting for detector upgrade (Oct) Monolayer shock experiments successful but difficult, need more development