1
|
Falcinelli S, Vecchiocattivi F, Pirani F. The topology of the reaction stereo-dynamics in chemi-ionizations. Commun Chem 2023; 6:30. [PMID: 36782019 PMCID: PMC9925729 DOI: 10.1038/s42004-023-00830-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 02/03/2023] [Indexed: 02/15/2023] Open
Abstract
Details on the stereo-dynamic topology of chemi-ionizations highlight the role of the centrifugal barrier of colliding reactants: it acts as a selector of the orbital quantum number effective for reaction in a state-to-state treatment. Here, an accurate internally consistent formulation of the Optical interaction potentials, obtained by the combined analysis of scattering and spectroscopic experimental findings, casts light on structure, energy and angular momentum couplings of the precursor (pre-reactive) state controlling the stereo-dynamics of prototypical chemi-ionization reactions. The closest approach (turning point) of reagents, is found to control the relative weight of two different reaction mechanisms: (i) A direct mechanism stimulated by exchange chemical forces mainly acting at short separation distances and high collision energy; (ii) An indirect mechanism, caused by the combination of weak chemical and physical forces dominant at larger distances, mainly probed at low collision energy, that can be triggered by a virtual photon exchange between reagents.
Collapse
Affiliation(s)
- Stefano Falcinelli
- Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125, Perugia, Italy.
| | - Franco Vecchiocattivi
- grid.9027.c0000 0004 1757 3630Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125 Perugia, Italy
| | - Fernando Pirani
- grid.9027.c0000 0004 1757 3630Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125 Perugia, Italy ,grid.9027.c0000 0004 1757 3630Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
| |
Collapse
|
2
|
Zou J, Gordon SDS, Osterwalder A. Sub-Kelvin Stereodynamics of the Ne(^{3}P_{2})+N_{2} Reaction. PHYSICAL REVIEW LETTERS 2019; 123:133401. [PMID: 31697548 DOI: 10.1103/physrevlett.123.133401] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Indexed: 06/10/2023]
Abstract
We present an experimental study of the low-energy stereodynamics of the Ne(^{3}P_{2})+N_{2} reaction. Supersonic expansions of the two reactants are superposed in a merged beam experiment, where individual velocity control of the two beams allows us to reach average relative velocities of zero, yielding minimum collision energies around 60 mK. We combine the merged beam technique with the orientation of the metastable neon atoms and measure the branching between two reaction channels, Penning ionization and associative ionization, as a function of neon orientation and collision energy, covering the range 0.06-700 K. We find that we lose the ability to orient Ne below ≈100 K due to dynamic reorientation. Associative ionization products Ne-N_{2}^{+} predissociate with a probability of 30%-60% and that associative ionization is entirely due to reactions of the Ω=2 state, where the singly occupied p orbital of the Ne^{*} is oriented along the interatomic axis.
Collapse
Affiliation(s)
- Junwen Zou
- Institute for Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Sean D S Gordon
- Institute for Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Andreas Osterwalder
- Institute for Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| |
Collapse
|
3
|
Gordon SDS, Osterwalder A. Energy and orientation independence of the channel branching in Ne* + ND 3 chemi-ionisation. Phys Chem Chem Phys 2019; 21:14306-14310. [PMID: 30672916 DOI: 10.1039/c8cp06666c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Collisions of excited neon atoms with ammonia molecules can lead to two reaction processes, dissociative ionisation and Penning ionisation. Both processes result in the ionisation of the ammonia molecule and redistribution of the electronic energy into the internal ammonia ion rovibrational modes. We performed energy dependent, crossed-beam stereodynamics studies of the branching ratio between the two ionisation processes. It was found that the branching ratio is totally and completely insensitive to both the neon orientation and the collision energy across the range we sampled, 370-520 cm-1. The total lack of stereodynamics can be explained by the structure of the ammonia and that its orientation, which we do not attempt to control, is the critical factor in the reaction outcome.
Collapse
Affiliation(s)
- Sean D S Gordon
- Institute for Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
| | - Andreas Osterwalder
- Institute for Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
| |
Collapse
|
4
|
Falcinelli S, Pirani F, Candori P, Brunetti BG, Farrar JM, Vecchiocattivi F. A New Insight on Stereo-Dynamics of Penning Ionization Reactions. Front Chem 2019; 7:445. [PMID: 31275926 PMCID: PMC6591474 DOI: 10.3389/fchem.2019.00445] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 05/31/2019] [Indexed: 12/25/2022] Open
Abstract
Recent developments in the experimental study of Penning ionization reactions are presented here to cast light on basic aspects of the stereo-dynamics of the microscopic mechanisms involved. They concern the dependence of the reaction probability on the relative orientation of the atomic and molecular orbitals of reagents and products. The focus is on collisions between metastable Ne*(3P2, 0) atoms with other noble gas atoms or molecules, for which play a crucial role both the inner open-shell structure of Ne* and the HOMO orbitals of the partner. Their mutual orientation with respect to the intermolecular axis controls the characteristics of the intermolecular potential, which drives the collision dynamics and the reaction probability. The investigation of ionization processes of water, the prototype of hydrogenated molecules, suggested that the ground state of water ion is produced when Ne* approaches H2O perpendicularly to its plane. Conversely, collisions addressed toward the lone pair, aligned along the water C2v symmetry axis, generates electronically excited water ions. However, obtained results refer to a statistical/random orientation of the open shell ionic core of Ne*. Recently, the attention focused on the ionization of Kr or Xe by Ne*, for which we have been able to characterize the dependence on the collision energy of the branching ratio between probabilities of spin orbit resolved elementary processes. The combined analysis of measured PIES spectra suggested the occurrence of contributions from four different reaction channels, assigned to two distinct spin-orbit states of the Ne*(3P2, 0) reagent and two different spin-orbit states of the ionic M+(2P3/2, 1/2) products (M = Kr, Xe). The obtained results emphasized the reactivity change of 3P0 atoms with respect to 3P2, in producing ions in 2P3/2 and 2P1/2 sublevels, as a function of the collision energy. These findings have been assumed to arise from a critical balance of adiabatic and non-adiabatic effects that control formation and electronic rearrangement of the collision complex, respectively. From these results we are able to characterize for the first time, according to our knowledge, the state to state reaction probability for the ionization of Kr and Xe by Ne* in both 3P2 and 3P0 sublevels.
Collapse
Affiliation(s)
- Stefano Falcinelli
- Department of Civil and Environmental Engineering, University of Perugia, Perugia, Italy
| | - Fernando Pirani
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Perugia, Italy
| | - Pietro Candori
- Department of Civil and Environmental Engineering, University of Perugia, Perugia, Italy
| | - Brunetto G Brunetti
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Perugia, Italy
| | - James M Farrar
- Department of Chemistry, University of Rochester, Rochester, NY, United States
| | - Franco Vecchiocattivi
- Department of Civil and Environmental Engineering, University of Perugia, Perugia, Italy
| |
Collapse
|
5
|
Falcinelli S, Vecchiocattivi F, Pirani F. Adiabatic and Nonadiabatic Effects in the Transition States of State to State Autoionization Processes. PHYSICAL REVIEW LETTERS 2018; 121:163403. [PMID: 30387669 DOI: 10.1103/physrevlett.121.163403] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Indexed: 06/08/2023]
Abstract
The energy distribution of electrons, emitted from collisions between Ne^{*}(^{3}P_{2,0}) and Kr(^{1}S_{0}), have been measured under high resolution conditions in a crossed molecular beam apparatus containing a hemispherical electron analyzer as detector. The experimental results provide new insights on the electronic adiabatic and nonadiabatic effects in the stereodynamics of state to state atomic and molecular collisions, controlling relevant properties of the transition state of autoionization processes. In particular, while the adiabatic effects determine sequence, energy, and symmetry of quantum states accessible both to reagents and products, the nonadiabatic effects trigger the passage from entrance to exit channels.
Collapse
Affiliation(s)
- Stefano Falcinelli
- Dipartimento di Ingegneria Civile ed Ambientale, Università di Perugia, Via G. Duranti 93, 06125 Perugia, Italy
| | - Franco Vecchiocattivi
- Dipartimento di Ingegneria Civile ed Ambientale, Università di Perugia, Via G. Duranti 93, 06125 Perugia, Italy
| | - Fernando Pirani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
| |
Collapse
|
6
|
Falcinelli S, Candori P, Pirani F, Vecchiocattivi F. The role of charge transfer in the stability and reactivity of chemical systems from experimental findings. Phys Chem Chem Phys 2017; 19:6933-6944. [DOI: 10.1039/c7cp00614d] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Phenomena are described within a unifying picture, by isolating charge/electron transfer as an interaction component triggering chemical reactivity.
Collapse
Affiliation(s)
- S. Falcinelli
- Department of Civil and Environmental Engineering
- University of Perugia
- 06125 Perugia
- Italy
| | - P. Candori
- Department of Civil and Environmental Engineering
- University of Perugia
- 06125 Perugia
- Italy
| | - F. Pirani
- Department of Chemistry
- Biology and Biotechnologies
- University of Perugia
- 06123 Perugia
- Italy
| | - F. Vecchiocattivi
- Department of Civil and Environmental Engineering
- University of Perugia
- 06125 Perugia
- Italy
| |
Collapse
|
7
|
The escape of O+ ions from the atmosphere: An explanation of the observed ion density profiles on Mars. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.09.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
8
|
Falcinelli S, Alagia M, Farrar JM, Kalogerakis KS, Pirani F, Richter R, Schio L, Stranges S, Rosi M, Vecchiocattivi F. Angular and energy distributions of fragment ions in dissociative double photoionization of acetylene molecules in the 31.9-50.0 eV photon energy range. J Chem Phys 2016. [DOI: 10.1063/1.4962915] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Stefano Falcinelli
- Dipartimento di Ingegneria Civile ed Ambientale, Università di Perugia, 06125 Perugia, Italy
| | | | - James M. Farrar
- Department of Chemistry, University of Rochester, Rochester, New York 14627, USA
| | | | - Fernando Pirani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, 06123 Perugia, Italy
| | - Robert Richter
- Sincrotrone Trieste, Area Science Park, 34149 Basovizza, Trieste, Italy
| | - Luca Schio
- IOM CNR Laboratorio TASC, 34012 Trieste, Italy
| | - Stefano Stranges
- IOM CNR Laboratorio TASC, 34012 Trieste, Italy
- Dipartimento di Chimica e Tecnologia del Farmaco, Università di Roma “La Sapienza,” 00185 Rome, Italy
| | - Marzio Rosi
- Dipartimento di Ingegneria Civile ed Ambientale, Università di Perugia, 06125 Perugia, Italy
| | - Franco Vecchiocattivi
- Dipartimento di Ingegneria Civile ed Ambientale, Università di Perugia, 06125 Perugia, Italy
| |
Collapse
|
9
|
|
10
|
Falcinelli S, Rosi M, Cavalli S, Pirani F, Vecchiocattivi F. Stereoselectivity in Autoionization Reactions of Hydrogenated Molecules by Metastable Noble Gas Atoms: The Role of Electronic Couplings. Chemistry 2016; 22:12518-26. [PMID: 27470487 DOI: 10.1002/chem.201601811] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Indexed: 11/09/2022]
Abstract
Focus in the present paper is on the analysis of total and partial ionization cross sections, measured in absolute value as a function of the collision energy, representative of the probability of ionic product formation in selected electronic states in Ne*-H2 O, H2 S, and NH3 collisions. In order to characterize the imaginary part of the optical potential, related to electronic couplings, we generalize a methodology to obtain direct information on the opacity function of these reactions. Such a methodology has been recently exploited to test the real part of the optical potential (S. Falcinelli et al., Chem. Eur. J., 2016, 22, 764-771). Depending on the balance of noncovalent contributions, the real part controls the approach of neutral reactants, the removal of ionic products, and the structure of the transition state. Strength, range, and stereoselectivity of electronic couplings, triggering these and many other reactions, are directly obtained from the present investigation.
Collapse
Affiliation(s)
- Stefano Falcinelli
- Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125, Perugia, Italy.
| | - Marzio Rosi
- Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125, Perugia, Italy
| | - Simonetta Cavalli
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy
| | - Fernando Pirani
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy
| | - Franco Vecchiocattivi
- Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125, Perugia, Italy
| |
Collapse
|
11
|
Falcinelli S, Rosi M, Pirani F, Stranges D, Vecchiocattivi F. Measurements of Ionization Cross Sections by Molecular Beam Experiments: Information Content on the Imaginary Part of the Optical Potential. J Phys Chem A 2016; 120:5169-74. [PMID: 26938026 DOI: 10.1021/acs.jpca.6b00795] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this work, we present and analyze in detail new and recent ionization cross section and mass spectrum determinations, collected in the case of He*, Ne*-H2O, -H2S, and -NH3 ionizing collisions. These sets of data, obtained under the same experimental conditions, are relevant to identify differences in the autoionization stereodynamics of the three hydrogenated molecules and on the selective role of the imaginary part of the optical potential. We demonstrate that in these autoionization processes hydrogen and halogen bonds are competing because they are controlling both real and imaginary components of the optical potential that drives the complete reaction dynamics. In particular, we found that both components critically depend on the angular and radial approach between the reagent partners in determining the collision dynamics.
Collapse
Affiliation(s)
- Stefano Falcinelli
- Department of Civil and Environmental Engineering, University of Perugia , Via G. Duranti 93, 06125 Perugia, Italy
| | - Marzio Rosi
- Department of Civil and Environmental Engineering, University of Perugia , Via G. Duranti 93, 06125 Perugia, Italy
| | - Fernando Pirani
- Department of Chemistry, Biology and Biotechnologies, University of Perugia , Via Elce di Sotto, 8, 06123 Perugia, Italy
| | - Domenico Stranges
- Department of Chemistry, University of Rome "La Sapienza" , 00185 Rome, Italy
| | - Franco Vecchiocattivi
- Department of Civil and Environmental Engineering, University of Perugia , Via G. Duranti 93, 06125 Perugia, Italy
| |
Collapse
|
12
|
Falcinelli S, Bartocci A, Cavalli S, Pirani F, Vecchiocattivi F. Stereodynamics in the Collisional Autoionization of Water, Ammonia, and Hydrogen Sulfide with Metastable Rare Gas Atoms: Competition Between Intermolecular Halogen and Hydrogen Bonds. Chemistry 2015; 22:764-71. [DOI: 10.1002/chem.201503692] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Indexed: 11/07/2022]
|