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VERSION:2.0
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METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20260818T235216Z
UID:https://www.mpsd.mpg.de/events/45900/1086032
DTSTART:20260609T083000Z
DTEND:20260609T101500Z
CLASS:PUBLIC
CREATED:20260603T123348Z
DESCRIPTION:X-ray free-electron lasers (XFELs) provide unique opportunities
  to investigate nonequilibrium structural dynamics in nanoscale materials 
 with unprecedented spatial and temporal resolution. By recording diffracti
 on patterns from individual nanoparticles and nanocrystals\, XFEL-based me
 thods can reveal structural heterogeneity and transient lattice distortion
 s that are inaccessible to conventional ensemble-averaged techniques. This
  talk will discuss how XFEL single-particle imaging and serial femtosecond
  crystallography can be used to probe photoinduced structural dynamics in 
 semiconductor quantum dots and metallic nanoparticles. Using time resolved
  serial femtosecond crystallography (TR-SFX)\, we investigate ultrafast la
 ttice responses in colloidal semiconductor quantum dots. In recent experim
 ents on CsPbBr₃ quantum dots\, resonant optical excitation produced meas
 urable changes in diffraction intensities and Bragg peak profiles\, demons
 trating sensitivity to subtle photoinduced lattice distortions at the sing
 le-particle level [1].In parallel\, we apply XFEL single-particle imaging 
 to large ensembles of gold nanoparticles undergoing nonequilibrium process
 es such as growth and plasmon-induced melting. In these experiments\, each
  diffraction pattern originates from an individual particle\, and a single
  dataset can contain millions of snapshots. Unlike conventional methods th
 at primarily provide ensemble-averaged information\, single-particle imagi
 ng offers access to the full distribution of structures within the ensembl
 e. To extract structural information from these highly heterogeneous datas
 ets\, we developed a high-throughput reconstruction framework based on Mon
 te Carlo sampling of particle shape and orientation parameters. By combini
 ng diffraction patterns from millions of particles and exploiting geometri
 c correlations across the dataset\, the method reconstructs statistically 
 significant distributions of transient particle morphologies and reveals s
 tructural evolution pathways during nonequilibrium transformations [2]. To
 gether\, these examples illustrate how XFEL diffraction imaging\, combined
  with advanced analysis methodologies\, enables direct observation of stru
 ctural heterogeneity and ultrafast dynamics in nanomaterials. The talk wil
 l highlight both the experimental capabilities and computational challenge
 s of extracting transient structural information from large-scale XFEL dat
 asets. [1] Shen\, Zhou\, et al. "Direct Observation of the Exciton-Polaron
  in Single CsPbBr3 Quantum Dots." ACS nano 19.31 (2025): 28372-28382. [2] 
 Shen\, Zhou\, et al. "Resolving nonequilibrium shape variations among mill
 ions of gold nanoparticles." ACS nano 18.24 (2024): 15576-15589.\nSpeaker:
  Zhou Shen
LAST-MODIFIED:20260603T123659Z
LOCATION:MPSD Bldg. 900\, Room: Seminar Room 136
SUMMARY:MPSD Exchange: Probing Ultrafast Structural Dynamics in Nanomateria
 ls with XFEL Diffraction Imaging 
URL;VALUE=URI:https://www.mpsd.mpg.de/events/45900/1086032
END:VEVENT
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