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Title: Spectroscopic observation and ultrafast coherent vibrational dynamics of the aqueous phenylalanine radical
Authors: Muhammad Shafiq Mohd Yusof
Siow, Jing Xuan
Yang, Ningchen
Chan, Wei Xin
Loh, Zhi-Heng
Keywords: Science::Chemistry
Issue Date: 2022
Source: Muhammad Shafiq Mohd Yusof, Siow, J. X., Yang, N., Chan, W. X. & Loh, Z. (2022). Spectroscopic observation and ultrafast coherent vibrational dynamics of the aqueous phenylalanine radical. Physical Chemistry Chemical Physics, 24(5), 2800-2812.
Project: RG1/20 
Journal: Physical Chemistry Chemical Physics 
Abstract: The phenylalanine radical (Phe˙) has been proposed to mediate biological electron transport (ET) and exhibit long-lived electronic coherences following attosecond photoionization. However, the coupling of ultrafast structural reorganization to the oxidation/ionization of biomolecules such as phenylalanine remains unexplored. Moreover, studies of ET involving Phe˙ are hindered by its hitherto unobserved electronic spectrum. Here, we report the spectroscopic observation and coherent vibrational dynamics of aqueous Phe˙, prepared by sub-6 fs photodetachment of phenylalaninate anions. Sub-picosecond transient absorption spectroscopy reveals the ultraviolet absorption signature of Phe˙. Ultrafast structural reorganization drives coherent vibrational motion involving nine fundamental frequencies and one overtone. DFT calculations rationalize the absence of the decarboxylation reaction, a photodegradation pathway previously identified for Phe˙. Our findings guide the interpretation of future attosecond experiments aimed at elucidating coherent electron motion in photoionized aqueous biomolecules and pave way for the spectroscopic identification of Phe˙ in studies of biological ET.
ISSN: 1463-9076
DOI: 10.1039/d1cp04326a
Schools: School of Physical and Mathematical Sciences 
Rights: © 2022 The Owner Societies. All rights reserved. This paper was published by Royal Society of Chemistry in Physical Chemistry Chemical Physics and is made available with permission of The Owner Societies.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SPMS Journal Articles

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