122nd General Meeting of the KCS

Type Oral Presentation
Area Oral Presentation for Young Scholars in Physical Chemistry
Room No. Room 324A
Time THU 10:48-:
Code PHYS.O-10
Subject Ultrafast measurement of transient absorption and refraction spectra with frequency comb in femtosecond to nanosecond time window
Authors Junwoo Kim, Minhaeng Cho1,*
Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science, Korea
1Department of Chemistry, Korea University, Korea
Abstract Transient absorption (TA) is the most widely utilized time-resolved spectroscopy technique for studying various photochemical reactions. Basically, TA is a pump-probe type experiment that a probe monitors the changes in spectral response induced by a pump with varying the optical time-delay between the pump and probe, T. Typical TA experiment controls T by a mechanical translational stage, while a dispersive spectrometer records the probe spectrum at each T. Recently, we developed dual frequency-comb (DFC) based interferometric pump-probe spectroscopy (DFC-IPS). DFC is consisted of two mode-locked lasers with highly stable two frequency degree of freedoms, repetition rate and carrier-envelope-offset frequency. By detuning the repetition rates of two lasers, which act as a pump and probe lasers, it is able to scan T linearly and automatically. The automatic T-scan is advantageous to study long-lasting dynamics because it preserves the spatial beam quality regardless of T. DFC-IPS can record a two-dimensional TA and transient refraction spectra with broad frequency (650 nm to 950 nm) and time window (12 fs to 10 ns) just in few seconds. Additionally, DFC-IPS data is simply measured by a single photodetector. This provides the capabilities for the experiments requiring parallel data acquisition, such as anisotropy and chirality measurement. These peculiar properties of DFC-IPS, the absence of mechanical T-scan and the use of single detector, make the experimental setup simpler than the typical TA experiment. Finally, a gated sampling is available in DFC-IPS, so that easily damageable photochemical reaction systems can also investigated.
E-mail jwkim0@korea.ac.kr