September 22nd (Thu) Graduate Seminar / Professor Heejae Kim

Ultrafast dynamics and control in condensed phase system

Optical spectroscopy is of essential approaches to information on material electronic properties, transport mechanism and structural configurations. With combinations of multiple light matter interactions, couplings among various entities in the condensed materials can be further disentangled. Moreover, by employing femtosecond (fs) laser-based optical techniques, one could observe the microscopic processes dominating ultrafast phenomena in real-time. In this seminar, I’ll briefly introduce the underlying principle for designing spectroscopic approaches and extracting essential information, and present examples of ultrafast dynamics in condensed phase systems [1]. One step further, light could even be an active player of controlling material properties by virtue of the recent development of high-intensity fs laser sources and phase stable pulse technology. I’ll illustrate examples of such controls via resonant and non-resonant pathways in a semiconductor system [2,3]. Finally, I will present our recent development of new two-dimensional spectroscopy which allows for unraveling the electron phonon interaction in an element-resolved fashion, and the potential of the technique toward fundamental understanding of both solid state and soft matter systems [4].

[References]

[1] H. Kim et al., Nat. Communs., 8, 687 (2017)

[2] H. Kim et al., App. Phys. Lett., 116, 201109 (2020)

[3] D. Berghoff et al., Nat. Communs., 12, 5719, (2021)