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Picosecond needs for phonon dynamics in nanoscience / energy science. Yuelin Li, X-ray Science Division, Argonne National Laboratory. Thermoelectricity and energy future. 90% of US power is from heat engines with efficiency at 30-40%, thus about 15 TW of heat is lost to the environment

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Picosecond needs for phonon dynamics in nanoscience energy science

Picosecond needs for phonon dynamics in nanoscience / energy science

Yuelin Li,

X-ray Science Division, Argonne National Laboratory


Thermoelectricity and energy future
Thermoelectricity and energy future

  • 90% of US power is from heat engines with efficiency at 30-40%, thus about 15 TW of heat is lost to the environment

  • Thermoelectric devices can potential convert part of these into electricity. At 1% level, this is equivalent to the total power of 100 1 GW nuclear power plants.

  • Solar thermoelectricity

  • However: efficiency/economics are the key

  • Figure of merit

    ZT=S2sT/k

    K: heat conductivity


Thermal electricity and nanoscience engineering in thermal electric systems
Thermal electricity and nanoscience: Engineering in thermal electric systems

  • Link the function and structure at nanoscale

  • Use nanostructure to manipulate energy carrier

    • Allow electrons to flow, block phonons

  • Figure of merit

    ZT=S2sT/k

Nanoscience research for energy needs: Report of the national naothechnology initiative grad challenge workshop, http://www.sc.doe.gov/BES/reports/files/NREN_rpt.pdf


Bottom up acoustic oscillation in a nanoparticles structures
Bottom upAcoustic oscillation in a nanoparticles/structures

  • Phonon = Lattice vibration

  • Lattice vibration of nanoparticles: optical methods

    • Oscillation period T: D (particle size)/ v (sound velocity)

      • For gold nano particles, eg., D=10 nm gives T=3 ps (v=3240 m/s )

      • Perner et al., ‘,’PRL 85, 792 (2000).

      • Vn Dijk et al., PRL 95, 267406 (2005).

      • Jerebtsov et al., PRB 76, 184301 (2007).

      • Courty, et al., Vibrational coherence of self-organized silver nanocrystals in f.c.c. supra-crystals. Nature Mater. 4, 395–398 (2005).

  • Vibration of nano super lattice

    • Layer structure, ps time scale

      • Trigo et al., ‘Probing Unfolded Acoustic Phonons with X-rays’, PRL. 101, 025505 (2008)

      • Bargheet et al., ‘Coherent Atomic Motions in a Nanostructure Studied by Femtosecond X-ray Diffraction,’ Science 306, 1771 (2004).

Self organized silver nanoparticle

and vibration

GaAs/AlGaAs superlattice


Bottom upapproach coupling of phonon oscillation between particle via plasmon oscillation
Bottom upapproachCoupling of phonon oscillation between particle via plasmon oscillation:

  • SPR/lattice vibration is dependent on the particle separation

Huang, et al., ‘The Effect of Plasmon Field on the Coherent Lattice Phonon

Oscillation in Electron-Beam Fabricated Gold Nanoparticle Pairs,’ Nano Letters20077 (10), 3227-3234


Top down approach materials with promising macroscopic property heat conductivity
Top-down approachMaterials with promising Macroscopic-property (heat conductivity)

  • Nano scale structures for low thermal conductivity (0.05 W m-1K-1), and ZT~2.4

    • Chiritescu et al., Ultralow Thermal Conductivity in Disordered, Layered WSe2 Crystals, SCIENCE 315, 351 (2007)

    • Hochbaum et al., ‘Enhanced thermoelectric performance of rough silicon nanowires’, Nature 451, 163 (2008)

    • Boukai et al., ‘Silicon nanowires as efficient thermoelectric materials,’ Nature 451, 168 (2008)

    • A. Majumdar, Thermoelectricity in semiconductor nanostructures, Science 303,777 (2004).

    • Venkatasubramanian, et al., Thin-film thermoelectric devices with high roomtemperature figures of merit, Nature 413, 597 (2001).

    • Harmon et al., Quantum dot superlattice thermoelectric materials and devices, Science 297, 2229 (2002).

  • Challenges

    • Phonon dynamics unknown

    • Very challenging to model (for all nano sctructures!)

Disordered WSe2 layers

Silicon naowires


Time resolved x ray measurement bridge the macro to nano scales phonon propagation
Time resolved x-ray measurement:Bridge the macro to nano scales: phonon/propagation

  • Heat = Phonon = Lattice vibration

    • Excite phonons: Laser pump

    • See phonons and propagation: x-ray probe with XRD, GISAX, ……

  • Requires ps resolution

    • Ultrafast lasers: Yes 

    • ps x-ray pulses: No 

    • ps detector: Y&N (streak camera at Sector. 7)

    • Theory and simulation

  • We already have other resources:

    • CNM, MSD, APS, U-Chicago, North-Western, and other

  • With the ps x-ray source, we can

    • better understand nanostructure for all purposes

    • design better thermoelectric material for future sustainable energy source

    • help others time resolved activities



Taking lcls into account
Taking LCLS into account

  • APS Short pulse/detector vs. LCLS

    • Pro:

      • Existing infrastructure and collaboration

      • Stability, availability

      • Higher average photon flux

      • Better sample survivability

    • Con

      • Low peak photon flux

      • Mentally less dazzling

  • LCLS pro and con

    • Pro

      • Shorter pulse with high photon flux

      • Mentally more dashing

    • Con

      • Availability and beam time allocation

      • Sample survivability

      • unwilling travel for users


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