Xiang gives a STEMinar talk on “What Do We See in Ultrafast Spectroscopy of Liquids?”
The seminar is scheduled for 4:30-5:30 PM, Wednesday, April 17 in Room 310, Pudong. Please also note that tea and coffee reception will start at 4:00 PM. VC will be ready in Room 375, Geo Building, Zhongbei Campus.
Abstract of the Talk:
The advancement of ultrafast laser techniques enables scientists to track molecular movements in real time, just like taking a series of snapshots with superfast shutter speed (compare with a femtosecond or 10-15 second). However, shooting a movie of all the molecules in a bulk liquid solution is not possible experimentally (which is possible in computer simulations), in fact, one can only focus on a few important motions. In this talk, I will introduce the concept of using ultrafast spectroscopy to study solvation dynamics, which is a relaxation process of the solvent after exciting the solute by a laser pulse. The traditional approach of studying solvation dynamics is called time-dependent fluorescence spectroscopy, which reports the evolution of solute’s emitted fluorescence. Still, one has to infer the changes in solvent structure from the concomitant evolution of the solute-solvent interaction energy. With the method we developed, it is now possible to measure directly how the solvent dynamics can be affected by electronically excitation of the solute. Combining laser excitation of solute with light scattering, we can follow the solvent structural dynamics via novel solute-pump/solvent-probe spectroscopy. From computer simulations of these spectra, we show that one can learn about local solvent structural changes near the newly excited solute.
Postdocs, students and your visitors are welcome also. We look forward to seeing you there.
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