Seminar

Chemical Reaction Dynamics Probed by Time-Resolved Vibrational Spectroscopy

조회수 : 551 등록일 : 2019.11.21 11:10

일시 : 2019.11.20 17:00
소속 : GIST 화학과
발표자 : 방윤수
장소 : R404

Ultrafast photophysical processes in the excited states including intramolecular proton transfers and charge transfers are of fundamental importance in understanding chemical reactions and many applications. In this work, ultrafast intramolecular proton transfer of 1,2-dihydroxyanthraquinone (alizarin) and intramolecular charge transfer of DCM dye and 1-aminoanthraquinone (AAQ) were visualized femtosecond stimulated Raman spectroscopy. From population and spectral changes of transient vibrational modes of the probe, structural changes of probe accompanying proton transfer or charge transfer can be obtained. Tautomerization of alizarin and twisted intramolecular charge transfer of DCM dye and AAQ will be discussed. We have also investigated the changes in the solvent vibrational modes of solvent DMSO during these ultrafast processes. The n(S=O) and n(CSC) mode substantially increase especially in the sub-bands for “aggregated” species of DMSO while a substantial decrease in the n(S=O) mode especially in the sub-bands for “hydrogen-bonded” species of DMSO was found during the intramolecular charge transfer of AAQ. In conclusion, we propose that the solvent vibrations of DMSO can be used as the measure of the chemical reaction dynamics of solute molecules and solvation dynamics accompanying the ultrafast photophysical processes.

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