119th General Meeting of the KCS

Type Oral Presentation
Area Oral Presentation for Young Scholars in Physical Chemistry
Room No. 304호
Time THU 10:47-:
Code PHYS.O-9
Subject Full Characterization of Ultrafast Excited-State Intramolecular Proton Transfer with Sub-10 fs Two-Color Transient Absorption Experiment
Authors 김준우, 주태하*
POSTECH 화학과, Korea
Abstract Excited-state intramolecular proton transfer (ESIPT) is a photo-induced tautomerization between the enol and keto form of the molecule. In general, ESIPT is has relatively faster reaction rate and larger Stokes shift than other photo-induced reactions. Because of these unique properties of ESIPT, it is applied for various fields, such as white light source, LED, molecular probe. Understanding of ESIPT dynamics can improve or modify its applications. Despite of its uniquity, its excited-state dynamics is not well understood by chemists. One main reason of that is the difficulty on studying a specific excited-state dynamics occurring in condensed phase. It is difficult to observe a specific dynamics, where it always accompanies other dynamics. In order to prevent the other dynamics interferes the observation of ESIPT, the system should have small and rigid structure and small charge transfer character in the excitation. In this research, 10-hydroxy[h]benzoquinoline (HBQ), which is well known for an ultrafast ESIPT system, is investigated as the fundamental study of ESIPT, where HBQ satisfies the conditions listed above. The excited-state dynamics of HBQ was measured with a NUV pump / visible continuum probe transient absorption (TA) apparatus, whose time resolution is sub 10 fs. By virtue of the high resolution, the Frank-Condon excitation induced vibrational spectrum (FEVS) of HBQ could be measured to 3000 cm-1. Since FEVS can be simulated by a simple quantum mechanical calculation, we compared the experimental and theoretical FEVS of HBQ and several important properties, such as electronic and nuclear structure, of HBQ can be obtained to conclude what are important factors in ESIPT.
E-mail jiudiungkim@postech.ac.kr