Heemin Lee
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View article: Surface-plasmon control of ultrafast energy-relaxation modes in photoexcited Au nanorods probed by time-resolved single-particle X-ray imaging
Surface-plasmon control of ultrafast energy-relaxation modes in photoexcited Au nanorods probed by time-resolved single-particle X-ray imaging Open
Ultrafast laser excitation can drive materials into exotic states beyond thermodynamic limits, offering alternative ways to control how matter stores and releases energy. Yet, whether light can actively steer energy-relaxation pathways dur…
View article: Introducing new resonant soft x-ray scattering capability in SSRL
Introducing new resonant soft x-ray scattering capability in SSRL Open
Resonant soft x-ray scattering (RSXS) is a powerful technique for probing both spatial and electronic structures within solid-state systems. We present a newly developed RSXS capability at beamline 13-3 of the Stanford Synchrotron Radiatio…
View article: Hidden dormant phase mediating the glass transition in disordered matter
Hidden dormant phase mediating the glass transition in disordered matter Open
Metallic glass is a frozen liquid with structural disorder that retains degenerate free energy without spontaneous symmetry breaking to become a solid. For over half a century, this puzzling structure has raised fundamental questions about…
View article: Photoinduced surface plasmon control of ultrafast melting modes in Au nanorods
Photoinduced surface plasmon control of ultrafast melting modes in Au nanorods Open
Photoinduced ultrafast phenomena in materials exhibiting nonequilibrium behavior can lead to the emergence of exotic phases beyond the limits of thermodynamics, presenting opportunities for femtosecond photoexcitation. Despite extensive re…
View article: Frustrated phonon with charge density wave in vanadium Kagome metal
Frustrated phonon with charge density wave in vanadium Kagome metal Open
The formation of a star of David CDW superstructure, resulting from the coordinated displacements of vanadium ions on a corner sharing triangular lattice, has garnered significant attention to comprehend the influence of electron phonon in…
View article: Inverted nucleation for photoinduced nonequilibrium melting
Inverted nucleation for photoinduced nonequilibrium melting Open
Ultrafast photoinduced melting provides an essential platform for studying nonequilibrium phase transitions by linking the kinetics of electron dynamics to ionic motions. Knowledge of dynamic balance in their energetics is essential to und…
View article: Emergence of liquid following laser melting of gold thin films
Emergence of liquid following laser melting of gold thin films Open
X-ray structural science is undergoing a revolution driven by the emergence of X-ray Free-electron Laser (XFEL) facilities. The structures of crystalline solids can now be studied on the picosecond time scale relevant to phonons, atomic vi…
View article: Observing femtosecond orbital dynamics in ultrafast Ge melting with time-resolved resonant X-ray scattering
Observing femtosecond orbital dynamics in ultrafast Ge melting with time-resolved resonant X-ray scattering Open
Photoinduced nonequilibrium phase transitions have stimulated interest in the dynamic interactions between electrons and crystalline ions, which have long been overlooked within the Born–Oppenheimer approximation. Ultrafast melting before …
View article: Compressive effects in melting of palladium thin films studied by ultrafast x-ray diffraction
Compressive effects in melting of palladium thin films studied by ultrafast x-ray diffraction Open
With the advent of x-ray free electron lasers (XFELs), ultrafast laser excitation leading to nonequilibrium states has become an important way to investigate thermal processes. Here, we use ultrafast x-ray diffraction in an XFEL pump-probe…
View article: Natural Products as New Approaches for Treating Bladder Cancer: From Traditional Medicine to Novel Drug Discovery
Natural Products as New Approaches for Treating Bladder Cancer: From Traditional Medicine to Novel Drug Discovery Open
Bladder cancer (BC) is a heterogeneous disease that a tumor develops in the bladder lining and in some cases, the bladder muscle. Chemotherapy and immunotherapy are commonly used to treat bladder cancer. However, chemotherapy can cause bur…
View article: Characterization of photoinduced normal state through charge density wave in superconducting YBa <sub>2</sub> Cu <sub>3</sub> O <sub>6.67</sub>
Characterization of photoinduced normal state through charge density wave in superconducting YBa <sub>2</sub> Cu <sub>3</sub> O <sub>6.67</sub> Open
The normal state of high- T c cuprates has been considered one of the essential topics in high-temperature superconductivity research. However, compared to the high magnetic field study of it, understanding a photoinduced normal state rema…
View article: Inducing thermodynamically blocked atomic ordering via strongly driven nonequilibrium kinetics
Inducing thermodynamically blocked atomic ordering via strongly driven nonequilibrium kinetics Open
Ultrafast laser–excited nanoparticle images reveal nonequilibrium kinetics–driven unusual surface ordering at high temperature.
View article: Stochastic chromatin packing of 3D mitotic chromosomes revealed by coherent X-rays
Stochastic chromatin packing of 3D mitotic chromosomes revealed by coherent X-rays Open
Significance The structural link between meter-long DNA molecules and chromosomes a few microns in size and their highly space-effective and fault-free packing and unpacking mechanisms remain a puzzle. This research addressed this fundamen…
View article: Single-Shot Coherent X-ray Imaging Instrument at PAL-XFEL
Single-Shot Coherent X-ray Imaging Instrument at PAL-XFEL Open
We developed a single-shot coherent X-ray imaging instrument at the hard X-ray beamline of the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL). This experimental platform was established to conduct a variety of XFEL expe…
View article: High-throughput ensemble characterization of individual core-shell nanoparticles with quantitative 3D density from XFEL single-particle imaging
High-throughput ensemble characterization of individual core-shell nanoparticles with quantitative 3D density from XFEL single-particle imaging Open
The structures, as building-blocks for designing functional nanomaterials, have fueled the development of versatile nanoprobes to understand local structures of noncrystalline specimens. Progresses in analyzing structures of individual spe…
View article: Ultrafast x-ray diffraction study of melt-front dynamics in polycrystalline thin films
Ultrafast x-ray diffraction study of melt-front dynamics in polycrystalline thin films Open
Laser melting of polycrystalline metals starts at the internal grain boundaries and propagates into the grains.
View article: Characterizing the intrinsic properties of individual XFEL pulses via single-particle diffraction
Characterizing the intrinsic properties of individual XFEL pulses via single-particle diffraction Open
With each single X-ray pulse having its own characteristics, understanding the individual property of each X-ray free-electron laser (XFEL) pulse is essential for its applications in probing and manipulating specimens as well as in diagnos…