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Jiang J. Diabatic Valence-Hole Concept. J Phys Chem A 2024; 128:3253-3265. [PMID: 38647413 DOI: 10.1021/acs.jpca.4c00289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
A global diabatization scheme, based on the "valence-hole" concept, has been previously applied to model webs of avoided crossings that exist in four electronic-state symmetry manifolds of C2 (1Πg, 3Πg, 1Σu+, and 3Σu+). Here, this model is extended to the electronically excited states of four more molecules: CN (2Σ+), N2 (3Πu), SiC (3Π), and Si2 (3Πg). Many strangenesses in the spectroscopic observations (e.g., energy level structure, predissociation linewidths, and radiative lifetimes) for all four electronic state systems discussed here are accounted for by this unified model. The key concept of the model is valence-hole electron configurations: 3σ24σ11π45σ2 in CN (2Σ+), 2σg22σu11πu43σg21πg1 in N2 (3Πu), 5σ26σ17σ22π3 in SiC (3Π), and 4σg24σu15σg22πu3 in Si2 (3Πg), all of which have a triply occupied "valence-core" (i.e., 2σg22σu1 or the equivalent). These valence-hole configurations have a nominal bond order of three or higher and correlate with high-energy separated-atom limits with an np ← ns (n = 2, 3) promotion in one of the atomic constituents. On its way to dissociation, the strongly bound diabatic valence-hole state crosses multiple weakly bound or repulsive states, which belong to electron configurations with a completely filled valence-core. These curve crossings between diabatic potentials result in a network of many avoided crossings among multiple electronic states, analogous to the well-studied electronic structure landscape of ionic-covalent crossings in strongly ionic molecules. Considering the unique role of valence-hole states in shaping the global electronic structure, the valence-hole concept should be added to our intuitive framework of chemical bonding.
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Affiliation(s)
- Jun Jiang
- Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
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2
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Heays AN, Lewis BR, de Oliveira N, Ubachs W. The spin-forbidden vacuum-ultraviolet absorption spectrum of 14N 15N. J Chem Phys 2019; 151:224305. [PMID: 31837671 DOI: 10.1063/1.5130206] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Photoabsorption spectra of 14N15N were recorded at high resolution with a vacuum-ultraviolet Fourier-transform spectrometer fed by synchrotron radiation in the range of 81-100 nm. The combination of high column density (3 × 1017 cm-2) and low temperature (98 K) allowed for the recording of weak spin-forbidden absorption bands' exciting levels of triplet character. The triplet states borrow intensity from 1Πu states of Rydberg and valence character while causing their predissociation. New predissociation linewidths and molecular constants are obtained for the states C3Πu(v = 7, 8, 14, 15, 16, 21), G3Πu(v = 0, 1, 4), and F3Πu(v = 0). The positions and widths of these levels are shown to be well-predicted by a coupled-Schrödinger equation model with empirical parameters based on experimental data on 14N2 and 15N2 triplet levels.
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Affiliation(s)
- A N Heays
- Department of Physics and Astronomy, and LaserLaB, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - B R Lewis
- Research School of Physics and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - N de Oliveira
- Synchrotron Soleil, Orme des Merisiers, St. Aubin, BP 48, 91192 Gif sur Yvette Cedex, France
| | - W Ubachs
- Department of Physics and Astronomy, and LaserLaB, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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Dörfler AD, Eberle P, Koner D, Tomza M, Meuwly M, Willitsch S. Long-range versus short-range effects in cold molecular ion-neutral collisions. Nat Commun 2019; 10:5429. [PMID: 31780657 PMCID: PMC6882903 DOI: 10.1038/s41467-019-13218-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 10/28/2019] [Indexed: 12/27/2022] Open
Abstract
The investigation of cold interactions between ions and neutrals has recently emerged as a new scientific frontier at the interface of physics and chemistry. Here, we report a study of charge-transfer (CT) collisions of Rb atoms with N\documentclass[12pt]{minimal}
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\begin{document}$${}_{2}^{+}$$\end{document}2+ and O\documentclass[12pt]{minimal}
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\begin{document}$${}_{2}^{+}$$\end{document}2+ ions in the mK regime using a dynamic ion-neutral hybrid trapping experiment. We observe markedly different CT kinetics and dynamics for the different systems and reaction channels studied. While the kinetics in some channels are consistent with classical capture theory, others show distinct non-universal dynamics. The experimental results are interpreted with the help of classical-capture, quasiclassical-trajectory and quantum-scattering calculations using ab-initio potentials for the highly excited molecular states involved. The theoretical analysis reveals an intricate interplay between short- and long-range effects in the different reaction channels which ultimately determines the CT dynamics and rates. Our results illustrate salient mechanisms that determine the efficiency of cold molecular CT reactions. Studies on reactions between cold molecular ions and neutral atoms provide insights into intermolecular interactions. Here the authors explore the kinetics and dynamics of charge-transfer collisions between the cold N\documentclass[12pt]{minimal}
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\begin{document}$${}_{2}^{+}$$\end{document}2+ and O\documentclass[12pt]{minimal}
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\begin{document}$${}_{2}^{+}$$\end{document}2+ ions and neutral Rb atoms and discuss the role of long- and short-range effects.
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Affiliation(s)
- Alexander D Dörfler
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland
| | - Pascal Eberle
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland
| | - Debasish Koner
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland
| | - Michał Tomza
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland.
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland.
| | - Stefan Willitsch
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056, Basel, Switzerland.
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Hall FHJ, Willitsch S. Millikelvin reactive collisions between sympathetically cooled molecular ions and laser-cooled atoms in an ion-atom hybrid trap. PHYSICAL REVIEW LETTERS 2012; 109:233202. [PMID: 23368197 DOI: 10.1103/physrevlett.109.233202] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Indexed: 06/01/2023]
Abstract
We report on a study of cold reactive collisions between sympathetically cooled molecular ions and laser-cooled atoms in an ion-atom hybrid trap. Chemical reactions were studied at average collision energies <E(coll)>/k(B)>/~20 mK, about 2 orders of magnitude lower than has been achieved in previous experiments with molecular ions. Choosing N(2)(+)+Rb as a prototypical system, we find that the reaction rate is independent of the collision energy within the range studied, but strongly dependent on the internal state of Rb. Highly efficient charge exchange four times faster than the Langevin rate was observed with Rb in the excited (5p) (2)P(3/2) state. This observation is rationalized by a capture process dominated by the charge-quadrupole interaction and a near resonance between the entrance and exit channels of the system. Our results provide a test of classical models for reactions of molecular ions at the lowest energies reached thus far.
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Affiliation(s)
- Felix H J Hall
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
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Salumbides EJ, Khramov A, Ubachs W. High-Resolution 2 + 1 REMPI Study of the a′′1Σg+ State in N2. J Phys Chem A 2009; 113:2383-6. [DOI: 10.1021/jp808698u] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- E. J. Salumbides
- Laser Centre, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - A. Khramov
- Laser Centre, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - W. Ubachs
- Laser Centre, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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Lewis BR, Baldwin KGH, Heays AN, Gibson ST, Sprengers JP, Ubachs W, Fujitake M. Structure and predissociation of the 3pσuD Σ3u+ Rydberg state of N2: First extreme-ultraviolet and new near-infrared observations, with coupled-channels analysis. J Chem Phys 2008; 129:204303. [DOI: 10.1063/1.3023034] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Lewis BR, Heays AN, Gibson ST, Lefebvre-Brion H, Lefebvre R. A coupled-channel model of the 3Pi(u) states of N2: structure and interactions of the 3ssigma(g)F3 3Pi(u) and 3ppi(u)G3 3Pi(u) Rydberg states. J Chem Phys 2008; 129:164306. [PMID: 19045265 DOI: 10.1063/1.2990656] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
New and existing spectroscopic data on N(2), obtained using a wide variety of experimental techniques, are interpreted using a coupled-channel Schrodinger-equation (CSE) model of the structure and predissociation dynamics for the interacting Rydberg and valence states of (3)Pi(u) symmetry. As a result, v>0 levels of the 3ppi(u)G(3) (3)Pi(u) Rydberg state are assigned correctly for the first time, leading to the identification of very strong perturbations in the G(3)-state vibrational structure. A four-channel CSE model, which includes the 3ssigma(g)F(3) (3)Pi(u) and 3ppi(u)G(3) (3)Pi(u) Rydberg states and the C(') (3)Pi(u) and C (3)Pi(u) valence states, indicates strong Rydberg-Rydberg coupling between the F(3) and G(3) states, strong Rydberg-valence coupling between the G(3) and C(') states, and weaker coupling between the F(3) and C(') states.
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Affiliation(s)
- B R Lewis
- Research School of Physical Sciences and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia.
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Lewis BR, Baldwin KGH, Sprengers JP, Ubachs W, Stark G, Yoshino K. Optical observation of the C, 3ssigma(g)F3, and 3ppi(u)G3 3Pi(u) states of N2. J Chem Phys 2008; 129:164305. [PMID: 19045264 DOI: 10.1063/1.2990655] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
High-resolution laser-based one extreme-ultraviolet (EUV)+one UV two-photon ionization spectroscopy and EUV photoabsorption spectroscopy have been employed to study spin-forbidden (3)Pi(u)-X (1)Sigma(g) (+)(v,0) transitions in (14)N(2) and (15)N(2). Levels of the C (3)Pi(u) valence and 3ssigma(g)F(3) and 3ppi(u)G(3) (3)Pi(u) Rydberg states are characterized, either through their direct optical observation, or, indirectly, through their perturbative effects on the (1)Pi(u) and (1)Sigma(u) (+) states, which are accessible in dipole-allowed transitions. Optical observation of the G(3)-X(0,0) and (1,0) transitions is reported for the first time, together with evidence for six new vibrational levels of the C state. Following the recent observation of the F(3)-X(0,0) transition at rotational resolution [J. P. Sprengers et al., J. Chem. Phys. 123, 144315 (2005)], the F(3)(v=1) level is found to be responsible for a local perturbation in the rotational predissociation pattern of the b(') (1)Sigma(u) (+)(v=4) state. Despite their somewhat fragmentary nature, these new observations provide a valuable database on the (3)Pi(u) states of N(2) and their interactions which will help elucidate the predissociation mechanisms for the nitrogen molecule.
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Affiliation(s)
- B R Lewis
- Research School of Physical Sciences and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia.
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Vieitez MO, Ivanov TI, de Lange CA, Ubachs W, Heays AN, Lewis BR, Stark G. Interactions of the 3pπucΠu1(v=2) Rydberg-complex member in isotopic N2. J Chem Phys 2008; 128:134313. [DOI: 10.1063/1.2883955] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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Haverd VE, Lewis BR, Gibson ST, Stark G. Rotational effects in the band oscillator strengths and predissociation linewidths for the lowest Πu1–XΣg+1 transitions of N2. J Chem Phys 2005; 123:214304. [PMID: 16356045 DOI: 10.1063/1.2134704] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
A coupled-channel Schrodinger equation (CSE) model of N2 photodissociation, which includes the effects of all interactions between the b, c, and o 1Pi u and the C and C' 3Pi u states, is employed to study the effects of rotation on the lowest-upsilon 1Pi u-X 1Sigmag+(upsilon,0) band oscillator strengths and 1Pi u predissociation linewidths. Significant rotational dependences are found which are in excellent agreement with recent experimental results, where comparisons are possible. New extreme-ultraviolet (EUV) photoabsorption spectra of the key b 1Pi u<--X 1Sigmag +(3,0) transition of N2 are also presented and analyzed, revealing a b(upsilon=3) predissociation linewidth peaking near J=11. This behavior can be reproduced only if the triplet structure of the C state is included explicitly in the CSE-model calculations, with a spin-orbit constant A approximately 15 cm(-1) for the diffuse C(upsilon=9) level which accidentally predissociates b(upsilon=3). The complex rotational behavior of the b-X(3,0) and other bands may be an important component in the modeling of EUV transmission through nitrogen-rich planetary atmospheres.
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Affiliation(s)
- V E Haverd
- Research School of Physical Sciences and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
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Sprengers JP, Reinhold E, Ubachs W, Baldwin KGH, Lewis BR. Optical observation of the 3sσgFΠu3 Rydberg state of N2. J Chem Phys 2005; 123:144315. [PMID: 16238399 DOI: 10.1063/1.2062189] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using ultrahigh-resolution 1 XUV+1 UV two-photon ionization laser spectroscopy, the F (3)Pi(u)<--X (1)Sigma(g) (+)(0,0) transition of N(2) has been optically observed for the first time, and the 3s sigma(g)F (3)Pi(u)(upsilon=0) Rydberg level fully characterized with rotational resolution. The experimental spectroscopic parameters and predissociation level widths suggest strong interactions between the F state and the 3p pi(u)G (3)Pi(u) Rydberg and C(') (3)Pi(u) valence states, analogous to those well known in the case of the isoconfigurational (1)Pi(u) states.
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Affiliation(s)
- J P Sprengers
- Laser Centre, Department of Physics and Astronomy, Vrije Universiteit, Amsterdam, The Netherlands
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Lewis BR, Gibson ST, Zhang W, Lefebvre-Brion H, Robbe JM. Predissociation mechanism for the lowest 1 Pi u states of N2. J Chem Phys 2005; 122:144302. [PMID: 15847518 DOI: 10.1063/1.1869986] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Separate coupled-channel Schrödinger-equation (CSE) models of the interacting (1)Pi(u) (b,c,o) and (3)Pi(u) (C,C(')) states of N(2) are combined, through the inclusion of spin-orbit interactions, to produce a five-channel CSE model of the N(2) predissociation. Comparison of the model calculations with an experimental database, consisting principally of detailed new measurements of the vibrational and isotopic dependence of the (1)Pi(u) linewidths and lifetimes, provides convincing evidence that the predissociation of the lowest (1)Pi(u) levels in N(2) is primarily an indirect process, involving spin-orbit coupling between the b (1)Pi(u)- and C (3)Pi(u)-state levels, the latter levels themselves heavily predissociated electrostatically by the C(') (3)Pi(u) continuum. The well-known large width of the b(v=3) level in (14)N(2) is caused by an accidental degeneracy with C(v=9). This CSE model provides the first quantitative explanation of the predissociation mechanism for the dipole-accessible (1)Pi(u) states of N(2), and is thus likely to prove useful in the construction of realistic radiative-transfer and photochemical models for nitrogen-rich planetary atmospheres.
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Affiliation(s)
- B R Lewis
- Research School of Physical Sciences and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
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van der Kamp AB, Siebbeles LDA, van der Zande WJ, Cosby PC. Evidence for predissociation of N2 a 1Πg(v≥7) by direct coupling to the A’ 5Σ+g state. J Chem Phys 1994. [DOI: 10.1063/1.468019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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