Journal Articles Journal of Physical Chemistry Letters Year : 2023

Photoionization Dynamics and Proton Transfer within the Adenine-Thymine Nucleobase Pair

Abstract

Studying the stability of hydrogen-bonded nucleobase pairs, at the heart of the genetic code, is of utmost importance for an in-depth understanding of basic mechanisms of life and biomolecular evolution. We present here a VUV single photon ionization dynamic study of the nucleobase pair adenine-thymine (AT), revealing its ionization and dissociative ionization thresholds via double imaging electron/ion coincidence spectroscopy. The experimental data, consisting of cluster mass-resolved threshold photoelectron spectra and photon energy-dependent ion kinetic energy release distributions, allow the unambiguous distinction of the dissociation of AT into protonated adenine AH+ and a dehydrogenated thymine radical T(−H) from dissociative ionization processes of other nucleobase clusters. Comparison to high-level ab initio calculations indicates that our experimental observations can be explained by a single hydrogen-bonded conformer present in our molecular beam and allows the estimation of an upper limit of the barrier of the proton transfer in the ionized AT pair.
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Dates and versions

hal-04414943 , version 1 (24-01-2024)

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Sebastian Hartweg, Majdi Hochlaf, Gustavo Garcia, Laurent Nahon. Photoionization Dynamics and Proton Transfer within the Adenine-Thymine Nucleobase Pair. Journal of Physical Chemistry Letters, 2023, 14 (15), pp.3698-3705. ⟨10.1021/acs.jpclett.3c00564⟩. ⟨hal-04414943⟩
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