Multi-photon and electron impact ionisation studies of reactivity in adenine–water clusters

Barc, B.; Ryszka, Michał; Poully, Jean‐Christophe; Maalouf, Elias Jabbour Al; Otell, Ziad El; Tabet, Jean Claude; Parajuli, Rajendra Prasad; Burgt, P J M van der; Limão-Vieira, P.; Cahillane, P.; Dampc, Marcin; Mason, Nigel J.; Eden, S.

doi:10.1016/j.ijms.2014.01.007

Cited by 13 publications

(27 citation statements)

References 48 publications

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“…In this ion Fig 5a). No peak at m/z 84 has been observed from isolated, clustered, or protonated adenine [22,37,39,40], or from protonated uracil [41]. The fact that the U + signals were the same (to within the uncertainty limits) in plots a and c as well as in plots b and d suggests that this result was not simply due to different populations of isolated uracil molecules in the neutral beams.…”

Section: Fig 5 Compares Mpi and Eii Measurements Carried Out On Uracmentioning

confidence: 81%

“…A convex lens on a slider was used to modify the laser spot diameter at the interaction with the molecular beam and hence control the fluence. This was previously estimated using simple ray diagrams for partially defocused measurements [11,22] but we did not have a reliable method to determine the spot diameter close to the focal point. This problem was solved by recording MPI signals as a function of the voltage on the reflection electrode (see Fig.1).…”

Section: Methodsmentioning

confidence: 99%

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Dissociative multi-photon ionization of isolated uracil and uracil-adenine complexes

Ryszka

Pandey

Rizk

et al. 2016

International Journal of Mass Spectrometry

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Recent multi-photon ionization (MPI) experiments on uracil revealed a fragment ion at m/z 84 that was proposed as a potential marker for ring opening in the electronically excited neutral molecule. The present MPI measurements on deuterated uracil identify the fragment as C 3 H 4 N 2 O + (uracil + less CO), a plausible dissociative ionization product from the theoretically predicted open-ring isomer. Equivalent measurements on thymine do not reveal an analogous CO loss channel, suggesting greater stability of the excited DNA base. MPI and electron impact ionization experiments have been carried out on uracil-adenine clusters in order to better understand the radiation response of uracil within RNA.Evidence for C 3 H 4 N 2 O + production from multi-photon-ionized uracil-adenine clusters is tentatively attributed to a significant population of π-stacked configurations in the neutral beam. Graphical AbstractHighlights UV multi-photon ionization measurements on deuterated uracil have identified a CO loss pathway that may indicate ring opening in the electronically excited neutral molecule. The first dissociative ionization experiments on uracil-adenine complexes have revealed that the CO loss channel is also accessible in these clusters.Keywords: Uracil; adenine-uracil clusters; fragmentation; multi-photon ionization; electron impact ionization; mass spectrometry Ryszka et al. Int. J. Mass. Spectrom. 396 (2016) 48 2 IntroductionThe dynamics and stabilities of nucleobases following excitation to their bright S 2 (ππ* of the ring-opening crossing seam [9] and the geometry of the predicted isomer indicates likely CO abstraction. Therefore MPI production of this fragment ion was proposed as a potential experimental marker for ring opening in neutral excited uracil, suggesting possibilities for diverse measurements exploring the process in depth (e.g. using coincidence and / or time-resolved methods). The first aim of the present work was to test if the new fragment ion is indeed due to CO loss by studying MPI of deuterated uracil (dominantly C 4 D 4 N 2 O 2 ). These results have the added value of identifying several previously debated fragments from the radical cation, while further evidence to assign specific peaks is provided by high-resolution MPI mass spectra. The paper also presents equivalent MPI measurements on thymine, for which no analogous ring-opening process has been predicted [9]. A distinctly higher pump energy (5.64 eV, 220 nm) was applied than in the previous MPI studies of thymine (4.34-4.77 eV, 285.7-260 nm) [6, 12, 13, 14, 15, 16, 17], increasing the likelihood of isomeric transitions during radiationless deactivation. Finally, MPI and electron impact ionization (EII) experiments were carried out on uracil-adenine clusters as a step towards better understanding the dissociative ionization pathways of uracil within RNA. Whereas several spectroscopic studies have been carried out on adenine-thymine complexes in supersonic beams [18,19,20], to our knowledge no previous experiments on isolated u...

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Section: Fig 5 Compares Mpi and Eii Measurements Carried Out On Uracmentioning

confidence: 81%

Section: Methodsmentioning

confidence: 99%

Dissociative multi-photon ionization of isolated uracil and uracil-adenine complexes

Ryszka

Pandey

Rizk

et al. 2016

International Journal of Mass Spectrometry

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“…The experimental system has been described in previous publications [5,17,18]. Briefly, argon carrier gas (1.1 bar) seeded with sublimated thymine (Sigma-Aldrich with stated purity ≥99%) expanded continuously through a 50 μm diameter pinhole into a pumped chamber (1000 l s −1 ) to form a supersonic jet.…”

Section: Methodsmentioning

confidence: 99%

“…Although studying DNA bases in the gas phase can lead to relatively clear interpretations, it represents a major step away from condensed macromolecular systems. Complementary studies of nucleotides [1], base pairs [2], and hydrated clusters [3][4][5] can enable closer analogies to be drawn with irradiated biological material. However, as cluster sources generally produce a broad distribution of conformations and sizes, characterizing the precursor of a specific product can present a significant challenge in experiments probing radiation-induced processes in clusters.…”

Section: Introductionmentioning

confidence: 99%

Stabilities of nanohydrated thymine radical cations: insights from multiphoton ionization experiments and ab initio calculations

et al. 2017

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Abstract. Multi-photon ionization experiments have been carried out on thymine-water clusters in the gas phase. Metastable H2O loss from T + (H2O)n was observed at n ≥ 3 only. Ab initio quantum-chemical calculations of a large range of optimized T + (H2O)n conformers have been performed up to n = 4, enabling binding energies of water to be derived. These decrease smoothly with n, consistent with the general trend of increasing metastable H2O loss in the experimental data. The lowest-energy conformers of T + (H2O)3 and T + (H2O)4 feature intermolecular bonding via charge-dipole interactions, in contrast with the purely hydrogen-bonded neutrals. We found no evidence for a closed hydration shell at n = 4, also contrasting with studies of neutral clusters.

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“…[1][2][3][4][5][6][7][8] Besides their relevance in atmospheric chemistry, [1] microhydrated protonated pyridine PyH + (H 2 O) n moieties are targeted here to study solvation effects in the frame of an investigation on the radiation action at the nanoscale. Besidest he fragmentation channel associated with the evaporation of water molecules, the charged-fragment mass spectrum shows competition between the production of the PyH + ion (or its corresponding charged fragments) and the production of H + (H 2 O) or H + (H 2 O) 2 ions.…”

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confidence: 99%

Proton Migration in Clusters Consisting of Protonated Pyridine Solvated by Water Molecules

et al. 2015

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Proton transfer (PT) from protonated pyridine to water molecules is observed after excitation of microhydrated protonated pyridine (Py) clusters PyH(+) (H2 O)n (n=0-5) is induced by a single collision with an Ar atom at high incident velocity (95×10(3) m s(-1) ). Besides the fragmentation channel associated with the evaporation of water molecules, the charged-fragment mass spectrum shows competition between the production of the PyH(+) ion (or its corresponding charged fragments) and the production of H(+) (H2 O) or H(+) (H2 O)2 ions. The increase in the production of protonated water fragments as a function of the number of H2 O molecules in the parent cluster ion as well sd the observation of a stable H(+) (H2 O)2 fragment, even in the case of the dissociation of PyH(+) (H2 O)2 , are evidence of the crucial role of PT in the relaxation process, even for a small number of solvating water molecules.

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Multi-photon and electron impact ionisation studies of reactivity in adenine–water clusters

Cited by 13 publications

References 48 publications

Dissociative multi-photon ionization of isolated uracil and uracil-adenine complexes

Dissociative multi-photon ionization of isolated uracil and uracil-adenine complexes

Stabilities of nanohydrated thymine radical cations: insights from multiphoton ionization experiments and ab initio calculations

Proton Migration in Clusters Consisting of Protonated Pyridine Solvated by Water Molecules

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