Physical Chemistry Seminar: Dr. Jiaojian Shi, SLAC National Accelerator Laboratory

About the Seminar

Ultrafast control of nanomaterials with terahertz-frequency light

Nanomaterials with a reduction in at least one dimension have exhibited novel properties beyond their bulk counterparts. For example, nanocrystals and two-dimensional semiconductors are making commercial inroads in diverse applications such as display, data storage, and energy conversion. Ultrafast terahertz-frequency (THz) laser pulses at picosecond (10-12 s) durations offer an enticing capability to control nanomaterials, fostering performance improvement and ushering in new applications, given that their timescales are commensurate with nanoscopic dynamics of electrons, lattice ions, etc. In this talk, I will show that THz-frequency pulses can control the universal photoluminescence blinking in single quantum dots, which remains an ongoing challenge despite decades of research. Then, I will present a novel nonresonant excitation approach for selective phase control beyond the traditional photoexcitation method at the absorption resonance, exemplified by THz-driven structural phase transitions in layered materials down to monolayer thickness at an ultrafast speed. Finally, I will delineate how the fundamental comprehension of THz interaction with quantum dots can be leveraged to produce a polarization-sensitive and low-cost THz camera with tantalizing commercialization prospects.

About the Speaker

Dr. Jiaojian Shi earned his B.S. in physics from Peking University in 2015 and his Ph.D. in chemistry from the Massachusetts Institute of Technology in 2021. While at MIT, he worked with Professor Keith A. Nelson on strong-field phenomena in low-dimensional materials at THz frequencies. Currently, he is a postdoctoral researcher in the group of Professor Aaron M. Lindenberg at Stanford University, where he focuses on studying THz-matter interactions with ultrafast structural-sensitive spectroscopies with sensitivity down to single-particle levels.