BEGIN:VCALENDAR
VERSION:2.0
PRODID:Icfo
X-PUBLISHED-TTL:P1W
BEGIN:VEVENT
UID:69e231a425780
DTSTART:20260127T090000Z
SEQUENCE:0
TRANSP:OPAQUE
LOCATION:Auditorium
SUMMARY:ICFO | YING-HAO CHIEN
CLASS:PUBLIC
DESCRIPTION:Since the invention of the integrated circuit (IC) in the 1950s
 \, modern civilization has been built upon its foundation. As ICs continue
  to scale down and operate at higher speeds\, managing heat dissipation an
 d energy transfer process is critical to overcoming performance limitation
 s and enabling the development of next-generation ICs. In classical models
 \, electrons and phonons are treated as independent systems to simplify ca
 lculations. This approximation successfully describes electronic band stru
 ctures\, charge transport\, and optical responses in many materials under 
 equilibrium conditions. However\, it neglects the critical role of electro
 n-phonon coupling\, a fundamental many-body interaction that governs non-e
 quilibrium energy exchange between electronic and lattice degrees of freed
 om. Recent advances in attosecond X-ray absorption fine structure (atto-XA
 FS) spectroscopy offer an unprecedented opportunity to observe electron-ph
 onon coupling dynamics with both attosecond temporal and element-specific 
 resolution. Hexagonal boron nitride (hBN)\, a widely studied prototypical 
 material with diverse applications\, still presents unresolved questions r
 egarding its ultrafast dynamics. In this work\, we investigate the coupled
  electron and phonon dynamics in bulk hBN using atto-XAFS. By employing di
 fferent excitation conditions and exploiting different temporal resolution
 s\, we disentangle the respective contributions of electrons and phonons t
 o the transient response\, demonstrating the unique capability of atto-XAF
 S to probe many-body dynamics in real-time. To enable further studies of n
 ovel materials\, we upgraded our titanium-doped sapphire (Ti:sapphire) chi
 rped pulse amplification (CPA) laser system\, integrated a new commercial 
 TOPAS optical parametric amplifier\, designed a novel microfluidics gas ta
 rget combined with a piezo pulse valve system aimed at reducing helium con
 sumption for high harmonic generation (HHG)\, implemented a cryogenic samp
 le mount for temperature-dependent measurements\, and replaced the diffrac
 tion grating in the soft X-ray spectrograph with high diffraction efficien
 cy and high resolving power reflection zone plates. We demonstrate the enh
 anced performance of the upgraded system for future advanced atto-XAFS exp
 eriments.\nTuesday January 27\, 10:00 h. ICFO Auditorium Thesis Director: 
 Prof. Dr. Jens Biegert
DTSTAMP:20260417T131204Z
END:VEVENT
END:VCALENDAR