https://scholar.dgist.ac.kr/handle/20.500.11750/46467 2026-04-08T16:46:56Z https://scholar.dgist.ac.kr/handle/20.500.11750/59031 Title: Integrative analysis framework for discerning oscillatory signals associated with molecular vibrations from time-resolved X-ray scattering data Author(s): Kim, Jaeseok; Jeong, Hyunwoo; Kim, Jong Goo Abstract: Understanding the fundamental motions of molecules, particularly vibrational motions, is essential for elucidating chemical reaction mechanisms. Time-resolved X-ray scattering (TRXS) has emerged as a powerful technique for investigating molecular vibrations, as it simultaneously provides both temporal and spatial information on vibrational modes. However, visualizing these vibrations via TRXS remains challenging due to technical limitations in achieving a high signal-to-noise ratio (SNR) and temporal resolution, making it difficult to resolve subtle oscillatory signals arising from molecular vibrations. Here, we present an integrative analysis framework developed to efficiently extract oscillatory signals from TRXS data and verify their association with molecular vibrations. The framework comprises two key steps: the extraction of oscillatory signals using singular spectrum analysis (SSA) and posterior structural analysis to assess the physical relevance of the extracted signals. By applying this scheme to simulated TRXS datasets, we demonstrate that it identifies oscillatory signals embedded in the data more effectively than conventional Fourier transform analysis, even under low SNR conditions. Furthermore, the structural analysis step effectively discriminates physically irrelevant components, such as harmonic and combination frequencies, and high-frequency artifacts from signals corresponding to the fundamental frequencies of molecular vibrations. The proposed data analysis framework is expected to advance studies of molecular vibrations and wavepacket dynamics using TRXS, ultimately providing deeper insights into the ultrafast reaction dynamics. 2025-08-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58963 Title: Unveiling hidden wavepacket dynamics in time-resolved x-ray scattering data via singular spectrum analysis Author(s): Kim, Jaeseok; Jeong, Hyunwoo; Lee, Jae Hyuk; Ma, Rory; Nam, Daewoong; Kim, Minseok; Jang, Dogeun; Kim, Jong Goo Abstract: Time-resolved x-ray liquidography (TRXL) is a powerful technique for directly tracking ultrafast structural dynamics in real space. However, resolving the motion of vibrational wavepackets generated by femtosecond laser pulses remains challenging due to the limited temporal resolution and signal-to-noise ratio (SNR) of experimental data. This study addresses these challenges by introducing singular spectrum analysis (SSA) as an efficient method for extracting oscillatory signals associated with vibrational wavepackets from TRXL data. To evaluate its performance, we conducted a comparative study using simulated TRXL data, demonstrating that SSA outperforms conventional analysis methods such as the Fourier transform of temporal profiles and singular value decomposition, particularly under low SNR conditions. We further applied SSA to experimental TRXL data on the photodissociation of triiodide (I-3(-) ) in methanol, successfully isolating oscillatory signals arising from wavepacket dynamics in ground-state I-3(-) and excited-state I-2(-), which had been challenging to resolve in previous TRXL studies. These results establish SSA as a highly effective tool for analyzing ultrafast structural dynamics in time-resolved experiments and open new opportunities for studying wavepacket dynamics in a wide range of photoinduced reactions. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution-NonCommercial 4.0International (CC BY-NC) license (https://creativecommons.org/licenses/by-nc/4.0/). 2025-06-30T15:00:00Z