Capturing transient species in ionized liquid water and aqueous solutions

The ionization of liquid water serves as the principal trigger for a myriad of phenomena that are relevant to radiation chemistry and radiation biology. The earliest events that follow the ionization of water, however, remain relatively unknown. By employing few-cycle pulses in the visible to near-i...

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Main Author: Loh, Zhi-Heng
Other Authors: Asian Spectroscopy Conference 2020
Format: Conference or Workshop Item
Language:English
Published: 2020
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Online Access:https://hdl.handle.net/10356/144258
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Institution: Nanyang Technological University
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spelling sg-ntu-dr.10356-1442582020-10-29T20:10:50Z Capturing transient species in ionized liquid water and aqueous solutions Loh, Zhi-Heng Asian Spectroscopy Conference 2020 Institute of Advanced Studies Science::Chemistry Hydrated Electron Proton Transfer The ionization of liquid water serves as the principal trigger for a myriad of phenomena that are relevant to radiation chemistry and radiation biology. The earliest events that follow the ionization of water, however, remain relatively unknown. By employing few-cycle pulses in the visible to near-infrared (500 – 900 nm) and the short-wave infrared (0.9 – 1.7 μm), we have performed a comprehensive probe of the fate of the electron that is initially injected into the conduction band by ionization. The results suggest that the relaxation of the conduction band electron to the hydrated s electron proceeds via an intermediate state, whose lifetime is found to be 77 ± 6 fs (118 ± 7 fs) in H2O (D2O). In complementary experiments, femtosecond soft X-ray free-electron laser probing at the oxygen K edge is employed to track the primary proton transfer reaction of ionized liquid water [1]. The experimental results suggest that H2O+ first undergoes proton transfer to yield vibrationally excited OH on the timescale of 46 ± 10 fs. Subsequent vibrational relaxation of OH occurs with a time constant of 0.18 ± 0.02 ps. Our studies of ionized liquid water have also been extended to anion photodetachment in aqueous solution. For example, in the case of phenoxide, which serves as a model for the redox-active amino acid tyrosine, photodetachment launches vibrational wave packet motion along multiple vibrational modes of the phenoxyl radical product [2]. Analysis of the vibrational wave packet dynamics reveals the normal modes that drive structural reorganization upon photodetachment. Our results shed light on the elementary ultrafast dynamics that accompany the interaction of ionizing radiation with molecules of biological relevance. Published version 2020-10-23T06:46:35Z 2020-10-23T06:46:35Z 2020 Conference Paper Loh, Z.-H. (2020). Capturing transient species in ionized liquid water and aqueous solutions. Proc. Of the 7th Asian Spectroscopy Conference (ASC 2020). doi:10.32655/ASC_8-10_Dec2020.30 https://hdl.handle.net/10356/144258 10.32655/ASC_8-10_Dec2020.30 en © 2020 Nanyang Technological University. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Science::Chemistry
Hydrated Electron
Proton Transfer
spellingShingle Science::Chemistry
Hydrated Electron
Proton Transfer
Loh, Zhi-Heng
Capturing transient species in ionized liquid water and aqueous solutions
description The ionization of liquid water serves as the principal trigger for a myriad of phenomena that are relevant to radiation chemistry and radiation biology. The earliest events that follow the ionization of water, however, remain relatively unknown. By employing few-cycle pulses in the visible to near-infrared (500 – 900 nm) and the short-wave infrared (0.9 – 1.7 μm), we have performed a comprehensive probe of the fate of the electron that is initially injected into the conduction band by ionization. The results suggest that the relaxation of the conduction band electron to the hydrated s electron proceeds via an intermediate state, whose lifetime is found to be 77 ± 6 fs (118 ± 7 fs) in H2O (D2O). In complementary experiments, femtosecond soft X-ray free-electron laser probing at the oxygen K edge is employed to track the primary proton transfer reaction of ionized liquid water [1]. The experimental results suggest that H2O+ first undergoes proton transfer to yield vibrationally excited OH on the timescale of 46 ± 10 fs. Subsequent vibrational relaxation of OH occurs with a time constant of 0.18 ± 0.02 ps. Our studies of ionized liquid water have also been extended to anion photodetachment in aqueous solution. For example, in the case of phenoxide, which serves as a model for the redox-active amino acid tyrosine, photodetachment launches vibrational wave packet motion along multiple vibrational modes of the phenoxyl radical product [2]. Analysis of the vibrational wave packet dynamics reveals the normal modes that drive structural reorganization upon photodetachment. Our results shed light on the elementary ultrafast dynamics that accompany the interaction of ionizing radiation with molecules of biological relevance.
author2 Asian Spectroscopy Conference 2020
author_facet Asian Spectroscopy Conference 2020
Loh, Zhi-Heng
format Conference or Workshop Item
author Loh, Zhi-Heng
author_sort Loh, Zhi-Heng
title Capturing transient species in ionized liquid water and aqueous solutions
title_short Capturing transient species in ionized liquid water and aqueous solutions
title_full Capturing transient species in ionized liquid water and aqueous solutions
title_fullStr Capturing transient species in ionized liquid water and aqueous solutions
title_full_unstemmed Capturing transient species in ionized liquid water and aqueous solutions
title_sort capturing transient species in ionized liquid water and aqueous solutions
publishDate 2020
url https://hdl.handle.net/10356/144258
_version_ 1683493251854630912