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Lozano AI, Kumar S, Pereira PJS, Kerkeni B, García G, Limão-Vieira P. Low-lying Negative Ion States Probed in Potassium - Ethanol Collisions. Chemphyschem 2024:e202400314. [PMID: 38630012 DOI: 10.1002/cphc.202400314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/17/2024] [Indexed: 05/23/2024]
Abstract
Dissociative electron transfer in collisions between neutral potassium atoms and neutral ethanol molecules yields mainly OH-, followed by C2H5O-, O-, CH3 - and CH2 -. The dynamics of negative ions have been investigated by recording time-of-flight mass spectra in a wide range of collision energies from 17.5 to 350 eV in the lab frame, where the branching ratios show a relevant energy dependence for low/intermediate collision energies. The dominant fragmentation channel in the whole energy range investigated has been assigned to the hydroxyl anion in contrast to oxygen anion from dissociative electron attachment (DEA) experiments. This result shows the relevant role of the electron donor in the vicinity of the temporary negative ion formed allowing access to reactions which are not thermodynamically attained in DEA experiments. The electronic state spectroscopy of such negative ions, was obtained from potassium cation energy loss spectra in the forward scattering direction at 205 eV impact energy, showing a prevalent Feshbach resonance at 9.36±0.10 eV withσ O H * / σ C H * ${{\sigma }_{OH}^{^{\ast}}/{\sigma }_{CH}^{^{\ast}}}$ character, while a less pronouncedσ O H * ${{\sigma }_{OH}^{^{\ast}}}$ contribution assigned to a shape resonance has been obtained at 3.16±0.10 eV. Quantum chemical calculations for the lowest-lying unoccupied molecular orbitals in the presence of a potassium atom have been performed to support the experimental findings.
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Affiliation(s)
- Ana Isabel Lozano
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516, Caparica, Portugal
- Institut de Recherche en Astrophysique et Planétologie (IRAP), Université Toulouse III - Paul Sabatier, CNRS, CNES, 9 Avenue du Colonel Roche, 31028 Toulouse, France
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, 94720, California, USA
| | - Sarvesh Kumar
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516, Caparica, Portugal
- Institut de Recherche en Astrophysique et Planétologie (IRAP), Université Toulouse III - Paul Sabatier, CNRS, CNES, 9 Avenue du Colonel Roche, 31028 Toulouse, France
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, 94720, California, USA
| | - Pedro J S Pereira
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516, Caparica, Portugal
- Institut de Recherche en Astrophysique et Planétologie (IRAP), Université Toulouse III - Paul Sabatier, CNRS, CNES, 9 Avenue du Colonel Roche, 31028 Toulouse, France
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, 94720, California, USA
- Department of Mathematics, Instituto Superior de Engenharia de Lisboa, R. Conselheiro Emídio Navarro 1, 1959-007, Lisboa, Portugal
| | - Boutheïna Kerkeni
- ISAMM, Université de la Manouba, La Manouba, 2010, Tunisia
- Département de Physique, LPMC, Faculté des Sciences de Tunis, Université de Tunis el Manar, Tunis, 2092, Tunisia
| | - Gustavo García
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas (CSIC), Serrano 113-bis, 28006, Madrid, Spain
| | - Paulo Limão-Vieira
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516, Caparica, Portugal
- Institut de Recherche en Astrophysique et Planétologie (IRAP), Université Toulouse III - Paul Sabatier, CNRS, CNES, 9 Avenue du Colonel Roche, 31028 Toulouse, France
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, 94720, California, USA
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Sensing the ortho Positions in C6Cl6 and C6H4Cl2 from Cl2− Formation upon Molecular Reduction. Molecules 2022; 27:molecules27154820. [PMID: 35956769 PMCID: PMC9369944 DOI: 10.3390/molecules27154820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 11/17/2022] Open
Abstract
The geometrical effect of chlorine atom positions in polyatomic molecules after capturing a low-energy electron is shown to be a prevalent mechanism yielding Cl2−. In this work, we investigated hexachlorobenzene reduction in electron transfer experiments to determine the role of chlorine atom positions around the aromatic ring, and compared our results with those using ortho-, meta- and para-dichlorobenzene molecules. This was achieved by combining gas-phase experiments to determine the reaction threshold by means of mass spectrometry together with quantum chemical calculations. We also observed that Cl2− formation can only occur in 1,2-C6H4Cl2, where the two closest C–Cl bonds are cleaved while the chlorine atoms are brought together within the ring framework due to excess energy dissipation. These results show that a strong coupling between electronic and C–Cl bending motion is responsible for a positional isomeric effect, where molecular recognition is a determining factor in chlorine anion formation.
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Stochastic dynamic quantitative and 3D structural matrix assisted laser desorption/ionization mass spectrometric analyses of mixture of nucleosides. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.132701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kumar S, Ben Chouikha I, Kerkeni B, García G, Limão-Vieira P. Bound Electron Enhanced Radiosensitisation of Nimorazole upon Charge Transfer. Molecules 2022; 27:molecules27134134. [PMID: 35807379 PMCID: PMC9268075 DOI: 10.3390/molecules27134134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 06/23/2022] [Accepted: 06/24/2022] [Indexed: 02/01/2023] Open
Abstract
This novel work reports nimorazole (NIMO) radiosensitizer reduction upon electron transfer in collisions with neutral potassium (K) atoms in the lab frame energy range of 10–400 eV. The negative ions formed in this energy range were time-of-flight mass analyzed and branching ratios were obtained. Assignment of different anions showed that more than 80% was due to the formation of the non-dissociated parent anion NIMO•− at 226 u and nitrogen dioxide anion NO2− at 46 u. The rich fragmentation pattern revealed that significant collision induced the decomposition of the 4-nitroimidazole ring, as well as other complex internal reactions within the temporary negative ion formed after electron transfer to neutral NIMO. Other fragment anions were only responsible for less than 20% of the total ion yield. Additional information on the electronic state spectroscopy of nimorazole was obtained by recording a K+ energy loss spectrum in the forward scattering direction (θ ≈ 0°), allowing us to determine the most accessible electronic states within the temporary negative ion. Quantum chemical calculations on the electronic structure of NIMO in the presence of a potassium atom were performed to help assign the most significant lowest unoccupied molecular orbitals participating in the collision process. Electron transfer was shown to be a relevant process for nimorazole radiosensitisation through efficient and prevalent non-dissociated parent anion formation.
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Affiliation(s)
- Sarvesh Kumar
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal;
| | - Islem Ben Chouikha
- Département de Physique, LPMC, Faculté des Sciences de Tunis, Université de Tunis el Manar, Tunis 2092, Tunisia;
| | - Boutheïna Kerkeni
- Département de Physique, LPMC, Faculté des Sciences de Tunis, Université de Tunis el Manar, Tunis 2092, Tunisia;
- ISAMM, Université de La Manouba, La Manouba 2010, Tunisia
- Correspondence: (B.K.); (P.L.-V.)
| | - Gustavo García
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 113-bis, 28006 Madrid, Spain;
| | - Paulo Limão-Vieira
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal;
- Correspondence: (B.K.); (P.L.-V.)
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Lozano AI, Kumar S, Kerkeni B, García G, Limão-Vieira P. Methanol Negative Ion Fragmentation Probed in Electron Transfer Experiments. J Phys Chem A 2022; 126:1076-1084. [PMID: 35143199 DOI: 10.1021/acs.jpca.1c07588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this contribution, we report a novel comprehensive investigation on negative ion formation from electron transfer processes mediated by neutral potassium atom collisions with neutral methanol molecules employing experimental and theoretical methodologies. Methanol collision-induced fragmentation yielding anion formation has been obtained by time-of-flight mass spectrometry in the wide energy range of 19 to 275 eV in the lab frame. The negative ions formed in such a collision process have been assigned to CH3O-, OH-, and O-, with a strong energy dependence especially at lower collision energies. The most intense fragment anions in the whole energy range investigated have been assigned to OH- and CH3O-. Additionally, the potassium cation energy loss spectrum in the forward scattering direction at 205 eV impact energy has revealed several features, where the two main electronic states accessible during the collision events have vertical electron affinities of -8.26 ± 0.20 and -10.36 ± 0.2 eV. Quantum chemical calculations have been performed for the lowest-lying unoccupied molecular orbitals of methanol in the presence of a potassium atom, lending strong support to the experimental findings.
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Affiliation(s)
- Ana Isabel Lozano
- Atomic and Molecular Collisions Laboratory, Centro de Física e Investigação Tecnológica, Department of Physics, Universidade NOVA de Lisboa, Caparica 2829-516, Portugal.,Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas (CSIC), Serrano 113-bis, Madrid 28006, Spain
| | - Sarvesh Kumar
- Atomic and Molecular Collisions Laboratory, Centro de Física e Investigação Tecnológica, Department of Physics, Universidade NOVA de Lisboa, Caparica 2829-516, Portugal
| | - Boutheïna Kerkeni
- Institut Supérieur des Arts Multimédia de la Manouba, Université de la Manouba, La Manouba 2010, Tunisia.,Département de Physique, Laboratoire de recherche: Physique de la matière condensée, Faculté des Sciences de Tunis, Université de Tunis el Manar, Tunis 2092, Tunisia
| | - Gustavo García
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas (CSIC), Serrano 113-bis, Madrid 28006, Spain
| | - Paulo Limão-Vieira
- Atomic and Molecular Collisions Laboratory, Centro de Física e Investigação Tecnológica, Department of Physics, Universidade NOVA de Lisboa, Caparica 2829-516, Portugal
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Erdmann E, Bacchus-Montabonel MC, Łabuda M. Modelling charge transfer processes in C 2+-tetrahydrofuran collision for ion-induced radiation damage in DNA building blocks. Phys Chem Chem Phys 2017; 19:19722-19732. [PMID: 28540940 DOI: 10.1039/c7cp02100c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Investigations of collision-induced processes involving carbon ions and molecules of biological interest, in particular DNA building blocks, are crucial to model the effect of radiation on cells in order to improve medical treatments for cancer therapy. Using carbon ions appears to be one of the most efficient ways to increase biological effectiveness to damage cancerous cells by irradiating deep-seated tumors. Therefore, interest in accurate calculations to understand fundamental processes occurring in ion-molecule collision systems has been growing recently. In this context, the charge transfer process in the collision of C2+(1s22s2) ions with the heterocyclic sugar moiety building block tetrahydrofuran (THF) was studied in order to interpret the mechanisms occurring at the molecular level. The molecular structure properties of THF were obtained by means of ab initio quantum chemistry methods. The role of the conformational structure and the orientation of the THF molecule in collision with C2+ ions are particularly discussed. Anisotropic effects of the process dynamics in the collision energy ranging from eV to keV by means of semiclassical treatment are also presented and compared to previous experimental and theoretical investigations. A detailed analysis of the obtained cross sections points out an increase in these values by three orders of magnitude by a change of the THF symmetry from C2v to Cs in collision with C2+, which determines a more efficient charge transfer in this case.
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Affiliation(s)
- Ewa Erdmann
- Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland.
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Limão-Vieira P, Duflot D, Hubin-Franskin MJ, Delwiche J, Hoffmann SV, Chiari L, Jones DB, Brunger MJ, Lopes MCA. Electronic states of tetrahydrofurfuryl alcohol (THFA) as studied by VUV spectroscopy and ab initio calculations. J Phys Chem A 2014; 118:6425-34. [PMID: 24742321 DOI: 10.1021/jp501634w] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The electronic spectroscopy of isolated tetrahydrofurfuryl alcohol (THFA) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 5.0-10.8 eV energy-range, with absolute cross-section measurements derived. The He(I) photoelectron spectrum was also collected to quantify ionization energies in the 9-16 eV spectral region. These experiments are supported by the first high-level ab initio calculations performed on the excited states of the neutral molecule and on the ground and excited state of the positive ion. The good agreement between the theoretical results and the measurements allows us to quantify for the first time the electronic-state spectroscopy of THFA. The present work also considers the question of the lowest energy conformers of the molecule and its population distribution at room temperature.
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Affiliation(s)
- P Limão-Vieira
- Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa , 2829-516 Caparica, Portugal
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Almeida D, Bacchus-Montabonel MC, da Silva FF, García G, Limão-Vieira P. Potassium-uracil/thymine ring cleavage enhancement as studied in electron transfer experiments and theoretical calculations. J Phys Chem A 2014; 118:6547-52. [PMID: 24818533 DOI: 10.1021/jp503164a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report experimental and theoretical studies on ring cleavage enhancement in collisions of potassium atoms with uracil/thymine to further increase the understanding of the complex mechanisms yielding such fragmentation pathways. In these electron transfer processes time-of-flight (TOF) negative ion mass spectra were obtained in the collision energy range 13.5-23.0 eV. We note that CNO(-) is the major ring breaking anion formed and its threshold formation is discussed within the collision energy range studied. Such a decomposition process is supported by the first theoretical calculations to clarify how DNA/RNA pyrimidine base fragmentation is enhanced in electron transfer processes yielding ion-pair formation.
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Affiliation(s)
- D Almeida
- Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa , 2829-516 Caparica, Portugal
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du Penhoat MAH, López-Tarifa P, Ghose KK, Jeanvoine Y, Gaigeot MP, Vuilleumier R, Politis MF, Bacchus-Montabonel MC. Modeling proton-induced damage on 2-deoxy-D-ribose. Conformational analysis. J Mol Model 2014; 20:2221. [DOI: 10.1007/s00894-014-2221-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 03/23/2014] [Indexed: 11/29/2022]
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Almeida D, Ferreira da Silva F, Eden S, García G, Limão-Vieira P. New Fragmentation Pathways in K–THF Collisions As Studied by Electron-Transfer Experiments: Negative Ion Formation. J Phys Chem A 2014; 118:690-6. [DOI: 10.1021/jp407997w] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- D. Almeida
- Laboratório
de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Fı́sica, Faculdade de Ciências
e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - F. Ferreira da Silva
- Laboratório
de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Fı́sica, Faculdade de Ciências
e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - S. Eden
- Department
of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, United Kingdom
| | - G. García
- Instituto de Fı́sica Fundamental, Consejo Superior de Investigaciones Cientı́ficas, Serrano 113-bis, 28006 Madrid, Spain
- Centre
for Medical Radiation Physics, University of Wollongong, NSW 2522, Australia
| | - P. Limão-Vieira
- Laboratório
de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Fı́sica, Faculdade de Ciências
e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
- Department
of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, United Kingdom
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Bacchus-Montabonel MC. Looking at radiation damage on prebiotic building blocks. J Phys Chem A 2013; 117:14169-75. [PMID: 24295208 DOI: 10.1021/jp4102948] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A number of complex organic molecules have been detected in the interstellar medium, as well as in meteorites or comets. Among them, some exobiologic-relevant molecules have attracted particular interest. In the hypothesis of an exogen transport of prebiotic building blocks at the origin of life, the survival of such species and particularly their resistance to the solar UV radiation or cosmic rays is a key issue. For that purpose, we have performed a theoretical approach of the charge transfer dynamics induced by collision of protons with nucleobases and the 2-deoxy-d-ribose sugar moiety in a wide collision energy range. Calculations have been carried out by means of ab initio quantum chemistry molecular methods and compared to previous theoretical results using carbon projectile ions. Qualitative trends can be exhibited on DNA or RNA building blocks damage, which may concern studies on prebiotic species under spatial radiation.
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