1
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Ard SG, Sweeny BC, Lewis TWR, Long BA, Viggiano AA, Shuman NS. A Common Bottleneck for Metal Oxidation by Molecular Oxygen Across Size Regimes: Kinetics of Atomic Lanthanide Cations (La +-Lu +) with O 2. J Phys Chem A 2024. [PMID: 38968412 DOI: 10.1021/acs.jpca.4c03777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2024]
Abstract
Kinetics of the lanthanide cations (Ln+ = La+-Lu+ excluding Pm+) reacting with molecular oxygen were measured in a selected-ion flow tube apparatus from 300 to 600 K. Where exothermic, these reactions occur efficiently, producing LnO+ + O. The reactions display positive temperature dependences consistent with Arrhenius equation behavior and show small activation energies (0-2 kJ mol-1) that are strongly correlated to promotion energies of the Ln+ atoms. Reanalysis of literature data on neutral Ln + O2 reactions show a similar correlation with slightly larger activation energies (0-10 kJ mol-1). The data are explained by a common mechanism controlling oxidation by molecular oxygen in these systems, as well as in gas-phase reactions of transition metal and posttransition metal cluster anions, neutral clusters deposited on surfaces, and for oxygen incident on metal surfaces. It is posited that across these systems, the height of an early barrier along the reaction coordinate is predictable based on knowledge of the electronic states of the reactants and may be used to either promote or inhibit oxygen activation.
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Affiliation(s)
- Shaun G Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Kirtland, New Mexico 87117, United States
| | - Brendan C Sweeny
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Kirtland, New Mexico 87117, United States
| | - Tucker W R Lewis
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Kirtland, New Mexico 87117, United States
| | - Bryan A Long
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Kirtland, New Mexico 87117, United States
| | - Albert A Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Kirtland, New Mexico 87117, United States
| | - Nicholas S Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Kirtland, New Mexico 87117, United States
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2
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Bubas AR, Zhang WJ, Armentrout PB. A guided ion beam investigation of UO2+ thermodynamics and f orbital participation: Reactions of U+ + CO2, UO+ + O2, and UO+ + CO. J Chem Phys 2023; 159:244305. [PMID: 38149740 DOI: 10.1063/5.0183836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 12/04/2023] [Indexed: 12/28/2023] Open
Abstract
A guided ion beam tandem mass spectrometer was employed to study the reactions of U+ + CO2, UO+ + O2, and the reverse of the former, UO+ + CO. Reaction cross sections as a function of kinetic energy over about a three order of magnitude range were studied for all systems. The reaction of U+ + CO2 proceeds to form UO+ + CO with an efficiency of 118% ± 24% as well as generating UO2+ + C and UCO+ + O. The reaction of UO+ + O2 forms UO2+ in an exothermic, barrierless process and also results in the collision-induced dissociation of UO+ to yield U+. In the UO+ + CO reaction, the formation of UO2+ in an endothermic process is the dominant reaction, but minor products of UCO+ + O and U+ + (O + CO) are also observed. Analysis of the kinetic energy dependences observed provides the bond energies, D0(U+-O) = 7.98 ± 0.22 and 8.05 ± 0.14 eV, D0(U+-CO) = 0.73 ± 0.13 eV, and D0(OU+-O) = 7.56 ± 0.12 eV. The values obtained for D0(U+-O) and D0(OU+-O) agree well with the previously reported literature values. To our knowledge, this is the first experimental measurement of D0(U+-CO). An analysis of the oxide bond energies shows that participation of 5f orbitals leads to a substantial increase in the thermodynamic stability of UO2+ relative to ThO2+ and especially transition metal dioxide cations.
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Affiliation(s)
- Amanda R Bubas
- Department of Chemistry, University of Utah, 315 S 1400 E Rm 2020, Salt Lake City, Utah 84112-0850, USA
| | - Wen-Jing Zhang
- Department of Chemistry, University of Utah, 315 S 1400 E Rm 2020, Salt Lake City, Utah 84112-0850, USA
| | - P B Armentrout
- Department of Chemistry, University of Utah, 315 S 1400 E Rm 2020, Salt Lake City, Utah 84112-0850, USA
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3
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Cox RM, Melby KM, French AD, Rodriguez MJ. f-Block reactions of metal cations with carbon dioxide studied by inductively coupled plasma tandem mass spectrometry. Phys Chem Chem Phys 2023; 26:209-218. [PMID: 38054255 DOI: 10.1039/d3cp04180h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
f-Block chemistry offers an opportunity to test current knowledge of chemical reactivity. The energy dependence of lanthanide cation (Ln+ = Ce+, Pr+, Nd+-Eu+) and actinide cation (An+ = Th+, U+-Am+) oxidation reactions by CO2, was observed by inductively coupled plasma tandem mass spectrometry. This reaction is commonly spin-unallowed because the neutral reactant (CO2, 1Σ+g) and product (CO, 1Σ+) require the metal and metal oxide cations to have the same spin state. Correlation of the promotion energy (Ep) to the first state with two free d-electrons with the reaction efficiency indicates that spin conservation is not a primary factor in the reaction rate. The Ep likely influences the reaction rate by partially setting the crossing between the ground and reactive states. Comparison of Ln+ and An+ congener reactivity indicates that the 5f-orbitals play a small role in the An+ reactions.
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Affiliation(s)
- Richard M Cox
- Pacific Northwest National Laboratory, Richland, WA 99352 USA, USA.
| | - Kali M Melby
- Pacific Northwest National Laboratory, Richland, WA 99352 USA, USA.
| | - Amanda D French
- Pacific Northwest National Laboratory, Richland, WA 99352 USA, USA.
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4
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Armentrout PB. Quantitative Aspects of Gas-Phase Metal Ion Chemistry: Conservation of Spin, Participation of f Orbitals, and C-H Activation and C-C Coupling. J Phys Chem A 2023; 127:9641-9653. [PMID: 37957118 DOI: 10.1021/acs.jpca.3c06023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
In this Featured Article, I reflect on over 40 years of guided ion beam tandem mass spectrometry (GIBMS) studies involving atomic metal cations and their clusters throughout the periodic table. Studies that have considered the role of spin conservation (or lack thereof) are a primary focus with a quantitative assessment of the effects examined. A need for state-specific studies of heavier elements is noted, as is a more quantitative assessment of spin-orbit interactions in reactivity. Because GIBMS experiments explicitly evaluate the kinetic energy dependence of reactions over a wide range, several interesting and unusual observations are highlighted. More detailed studies of such unusual reaction events would be welcome. Activation of C-H bonds and ensuing C-C coupling events are reviewed, with future work encouraged. Finally, studies of lanthanides and actinides are examined with an eye on understanding the role of f orbitals in the chemistry, both as participants (or not) in the bonding and as sources/sinks of electron density. This area seems to be ripe for more quantitative experiments.
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Affiliation(s)
- P B Armentrout
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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5
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Merriles DM, London A, Tieu E, Nielson C, Morse MD. Probing the Chemical Bond between Lanthanides and Carbon: CeC, PrC, NdC, LuC, and TmC 2. Inorg Chem 2023. [PMID: 37285469 DOI: 10.1021/acs.inorgchem.3c01042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Resonant two-photon ionization experiments have been conducted to probe the bond dissociation energy (BDE) of the lanthanide-carbon bond, allowing the BDEs of CeC, PrC, NdC, LuC, and Tm-C2 to be measured to high precision. Values of D0(CeC) = 4.893(3) eV, D0(PrC) = 4.052(3) eV, D0(NdC) = 3.596(3) eV, D0(LuC) = 3.685(4) eV, and D0(Tm-C2) = 4.797(6) eV are obtained. Additionally, the adiabatic ionization energy of LuC was measured, giving IE(LuC) = 7.05(3) eV. The electronic structure of these species, along with the previously measured LaC, has been further investigated using quantum chemical calculations. Despite LaC, CeC, PrC, and NdC having ground electronic configurations that differ only in the number of 4f electrons present and have virtually identical bond orders, bond lengths, fundamental stretching frequencies, and metallic oxidation states, a peculiar 1.30 eV range in bond dissociation energies exists for these molecules. A natural bond orbital analysis shows that the metal atoms in these molecules have a natural charge of +1 with a 5d2 4fn 6s0 configuration while the carbon atom has a natural charge of -1 and a 2p3 configuration. The diabatic bond dissociation energies, calculated with respect to the lowest energy level of this separated ion configuration, show a greatly reduced energy range of 0.32 eV, with the diabatic BDE decreasing as the amount of 4f character in the σ-bond increases. Thus, the wide range of measured BDEs for these molecules is a consequence of the variation in atomic promotion energies at the separated ion limit. TmC2 has a smaller BDE than the other LnC2 molecules, due to the tiny amount of 5d participation in the valence molecular orbitals.
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Affiliation(s)
- Dakota M Merriles
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Anthony London
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Erick Tieu
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Christopher Nielson
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Michael D Morse
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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6
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Ghiassee M, Christensen EG, Fenn T, Armentrout PB. Guided Ion Beam Studies of the Dy + O → DyO + + e - Chemi-ionization Reaction Thermochemistry and Dysprosium Oxide, Carbide, Sulfide, Dioxide, and Sulfoxide Cation Bond Energies. J Phys Chem A 2023; 127:169-180. [PMID: 36563115 DOI: 10.1021/acs.jpca.2c07638] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Guided ion beam tandem mass spectrometry (GIBMS) was used to measure the kinetic energy dependent product ion cross sections for reactions of the lanthanide metal dysprosium cation (Dy+) with O2, SO2, and CO and reactions of DyO+ with CO, O2, and Xe. DyO+ is formed through an exothermic process when Dy+ reacts with O2, whereas all other processes observed are found to be endothermic. The kinetic energy dependences of these cross sections were analyzed to yield 0 K bond dissociation energies (BDEs) for DyO+, DyC+, DyS+, DyO2+, and DySO+. The 0 K BDE for DyO+ is determined to be 5.60 ± 0.02 eV from the weighted average of six independent thresholds, which are dominated by the slightly endothermic reaction of Dy+ with SO2. Combined with the well-established Dy ionization energy (IE), this value indicates that the chemi-ionization reaction, Dy + O → DyO+ + e-, is endothermic by 0.33 ± 0.02 eV. Theoretical BDEs for Dy+-O, Dy+-C, Dy+-S, ODy+-O, and Dy+-SO were calculated at several levels of theory and basis sets for comparison with experiment with reasonable agreement achieved.
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Affiliation(s)
- Maryam Ghiassee
- Department of Chemistry, University of Utah, 315 S. 1400 E. Rm 2020, Salt Lake City, Utah84112, United States
| | - Elizabeth G Christensen
- Department of Chemistry, University of Utah, 315 S. 1400 E. Rm 2020, Salt Lake City, Utah84112, United States
| | - Talley Fenn
- Department of Chemistry, University of Utah, 315 S. 1400 E. Rm 2020, Salt Lake City, Utah84112, United States
| | - P B Armentrout
- Department of Chemistry, University of Utah, 315 S. 1400 E. Rm 2020, Salt Lake City, Utah84112, United States
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7
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Zhang Y, Nakamura T, Wu L, Wenjin Cao W, Schoendorff G, Gordon MS, Yang DS. Electronic states and transitions of PrO and PrO+ probed by threshold ionization spectroscopy and spin-orbit multiconfiguration perturbation theory. J Chem Phys 2022; 157:114304. [DOI: 10.1063/5.0113741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The precise ionization energy of praseodymium oxide (PrO) seeded in supersonic molecular beams is measured with mass-analyzed threshold ionization (MATI) spectroscopy. A total of 33 spin-orbit (SO) states of PrO and 23 SO states of PrO+ are predicted by second-order multiconfigurational quasi-degenerate perturbation (MCQDPT2) theory. Electronic transitions from four low-energy SO levels of the neutral molecule to the ground state of the singly charged cation are identified by combining the MATI spectroscopic measurements with the MCQDPT2 calculations. The precise ionization energy is used to reassess the ionization energies and the reaction enthalpies of the Pr + O → PrO+ + e- chemi-ionization reaction reported in the literature. An empirical formula that uses atomic electronic parameters is proposed to predict the ionization energies of lanthanide monooxides, and the empirical calculations match well with available precise experimental measurements.
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Affiliation(s)
- Yuchen Zhang
- Chemistry, University of Kentucky, United States of America
| | - Taiji Nakamura
- Gunma University Faculty of Engineering Graduate School of Engineering Department of Chemistry and Bioengineering, Japan
| | - Lu Wu
- University of Kentucky, United States of America
| | | | - George Schoendorff
- Propellants Branch, Rocket Propulsion Division, Air Force Research Laboratory Aerospace Systems Directorate Edwards AFB, United States of America
| | - Mark S. Gordon
- Department of Chemistry, Iowa State University, United States of America
| | - Dong-Sheng Yang
- Department of Chemistry, University of Kentucky, United States of America
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8
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Sweeny BC, Heaven MC, Lachowicz A, Johnson MA, Viggiano AA, Shuman NS, Ard SG. Gas-Phase Reactivity of Ozone with Lanthanide Ions (Sm +, Nd +) and Their Higher Oxides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:1401-1410. [PMID: 35545264 DOI: 10.1021/jasms.2c00058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The kinetics of SmOn+ (n = 0-2) and NdOn+ (n = 0-2) with O3 are measured using a selected-ion flow tube. Reaction of Nd+ to yield NdO+ + O2 occurs rapidly, with a rate constant near the capture-controlled limit of ∼8 × 10-10 cm3 s-1. NdO+ reacts at ∼40% of the capture limit to yield NdO2+ with little temperature dependence from 200 to 400 K. NdO2+ likely reacts very slowly (k ∼ 10-13 cm3 s-1) to yield NdO+ + 2O2, does not react to yield NdO3+, and associates slowly (k ∼ 10-12 cm3 s-1) to yield NdO2+(O3)1-3. Reaction of Sm+ also yields SmO+ at near the capture limit at all temperatures, but a significant fraction (∼50%) of the SmO+ is produced in excited states that are long-lived compared to the millisecond time scale of the experiment. These states are evidently resistant to both radiative and collisional relaxation. The excited-state production is likely due to a spin-conservation constraint on the reaction, despite the large spin-orbit coupling typical for lanthanide-containing species. Ground-state SmO+ reacts inefficiently (k = 2 × 10-11 (T/300)-2.5 cm3 s-1) to yield SmO2+ + O2, while the excited-state SmO+* reacts at the capture limit, with branching to yield Sm+ + 2O2 (ΔHr,0K = 148.7 ± 0.4 kJ mol-1 for ground-state SmO+) approximately 60% of the time, the remainder forming SmO2+, which further reacts with O3 to yield SmO+ at about 1% of the collisional value.
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Affiliation(s)
- Brendan C Sweeny
- Institute for Scientific Research, Boston College, Boston, Massachusetts 02467, United States
| | - Michael C Heaven
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Anton Lachowicz
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | - Mark A Johnson
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | - Albert A Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Kirtland AFB, New Mexico 87117, United States
| | - Nicholas S Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Kirtland AFB, New Mexico 87117, United States
| | - Shaun G Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Kirtland AFB, New Mexico 87117, United States
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9
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Armentrout PB. Periodic trends in gas-phase oxidation and hydrogenation reactions of lanthanides and 5d transition metal cations. MASS SPECTROMETRY REVIEWS 2022; 41:606-626. [PMID: 34028077 DOI: 10.1002/mas.21703] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/30/2021] [Accepted: 05/03/2021] [Indexed: 06/12/2023]
Affiliation(s)
- P B Armentrout
- Department of Chemistry, University of Utah, Salt Lake City, Utah, USA
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10
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Cox RM, Harouaka K, Citir M, Armentrout PB. Activation of CO 2 by Actinide Cations (Th +, U +, Pu +, and Am +) as Studied by Guided Ion Beam and Triple Quadrupole Mass Spectrometry. Inorg Chem 2022; 61:8168-8181. [PMID: 35536874 DOI: 10.1021/acs.inorgchem.2c00447] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reactions of CO2 with Th+ have been studied using guided ion beam tandem mass spectrometry (GIBMS) and with An+ (An+ = Th+, U+, Pu+, and Am+) using triple quadrupole inductively coupled plasma mass spectrometry (QQQ-ICP-MS). Additionally, the reactions ThO+ + CO and ThO+ + CO2 were examined using GIBMS. Modeling the kinetic energy-dependent GIBMS data allowed the determination of bond dissociation energies (BDEs) for D0(Th+-O) and D0(OTh+-O) that are in reasonable agreement with previous GIBMS measurements. The QQQ-ICP-MS reactions were studied at higher pressures where multiple collisions between An+ and the neutral CO2 occur. As a consequence, both AnO+ and AnO2+ products were observed for all An+ except Am+, where only AmO+ was observed. The relative abundances of the observed monoxides compared to the dioxides are consistent with previous reports of the AnOn+ (n = 1, 2) BDEs. A comparison of the periodic trends of the group 4 transition metal, lanthanide (Ln), and actinide atomic cations in reactions with CO2 (a formally spin-forbidden reaction for most M+ ground states) and O2 (a spin-unrestricted reaction) indicates that spin conservation plays a minor role, if any, for the heavier Ln+ and An+ metals. Further correlation of Ln+ and An+ + CO2 reaction efficiencies with the promotion energy (Ep) to the first electronic state with two valence d-electrons (Ep(5d2) for Ln+ and Ep(6d2) for An+) indicates that the primary limitation in the activation of CO2 is the energetic cost to promote from the electronic ground state of the atomic metal ion to a reactive state.
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Affiliation(s)
- Richard M Cox
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, United States.,Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Khadouja Harouaka
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Murat Citir
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, United States
| | - P B Armentrout
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, United States
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11
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Lachowicz A, Perez EH, Shuman NS, Ard SG, Viggiano AA, Armentrout PB, Goings JJ, Sharma P, Li X, Johnson MA. Determination of the SmO + bond energy by threshold photodissociation of the cryogenically cooled ion. J Chem Phys 2021; 155:174303. [PMID: 34742201 DOI: 10.1063/5.0068734] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The SmO+ bond energy has been measured by monitoring the threshold for photodissociation of the cryogenically cooled ion. The action spectrum features a very sharp onset, indicating a bond energy of 5.596 ± 0.004 eV. This value, when combined with the literature value of the samarium ionization energy, indicates that the chemi-ionization reaction of atomic Sm with atomic oxygen is endothermic by 0.048 ± 0.004 eV, which has important implications on the reactivity of Sm atoms released into the upper atmosphere. The SmO+ ion was prepared by electrospray ionization followed by collisional breakup of two different precursors and characterized by the vibrational spectrum of the He-tagged ion. The UV photodissociation threshold is similar for the 10 K bare ion and the He tagged ion, which rules out the possible role of metastable electronically excited states. Reanalysis and remeasurement of previous reaction kinetics experiments that are dependent on D0(SmO+) are included, bringing all experimental results in accord.
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Affiliation(s)
- Anton Lachowicz
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Evan H Perez
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Nicholas S Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, USA
| | - Shaun G Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, USA
| | - Albert A Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, USA
| | - P B Armentrout
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Joshua J Goings
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Prachi Sharma
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Xiaosong Li
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Mark A Johnson
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
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12
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Merriles DM, Tomchak KH, Ewigleben JC, Morse MD. Predissociation measurements of the bond dissociation energies of EuO, TmO, and YbO. J Chem Phys 2021; 155:144303. [PMID: 34654298 DOI: 10.1063/5.0068543] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The observation of a sharp predissociation threshold in the resonant two-photon ionization spectra of EuO, TmO, and YbO has been used to measure the bond dissociation energies of these species. The resulting values, D0(EuO) = 4.922(3) eV, D0(TmO) = 5.242(6) eV, and D0(YbO) = 4.083(3) eV, are in good agreement with previous values but are much more precise. In addition, the ionization energy of TmO was measured by the observation of a threshold for one-color two-photon ionization of this species, resulting in IE(TmO) = 6.56(2) eV. The observation of a sharp predissociation threshold for EuO was initially surprising because the half-filled 4f7 subshell of Eu in its ground state generates fewer potential energy curves than in the other molecules we have studied by this method. The observation of a sharp predissociation threshold in YbO was even more surprising, given that the ground state of Yb is nondegenerate (4f146s2, 1Sg) and the lowest excited state of Yb is over 2 eV higher in energy. It is suggested that these molecules possess a high density of electronic states at the energy of the ground separated atom limit because ion-pair states drop below the ground limit, providing a sufficient electronic state density to allow predissociation to set in at the thermochemical threshold.
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Affiliation(s)
- Dakota M Merriles
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Kimberly H Tomchak
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Joshua C Ewigleben
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Michael D Morse
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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13
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Owen CJ, Kim J, Armentrout PB. Holmium (Ho) oxide, carbide, and dioxide cation bond energies and evaluation of the Ho + O → HoO + + e - chemi-ionization reaction enthalpy. J Chem Phys 2021; 155:094303. [PMID: 34496594 DOI: 10.1063/5.0064141] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Guided ion beam tandem mass spectrometry (GIBMS) and quantum chemical calculations are employed to evaluate the title chemi-ionization reaction with holmium. Exchange reactions of Ho+ with O2, CO, and SO2 and HoO+ with CO, as well as collision-induced dissociation (CID) reactions of HoO+ with Xe, O2, and CO, were performed using GIBMS. Formation of HoO+ is exothermic in reactions with O2 and SO2 but endothermic for reaction with CO, as is the exchange reaction of HoO+ with CO. Quantitative analysis of these reactions and the three CID reactions provides a robust method to determine the bond dissociation energy (BDE) of Ho+-O, 6.02 ± 0.13 eV. BDEs for Ho+-C and OHo+-O are also measured as 2.27 ± 0.19 and 2.70 ± 0.27 eV, respectively. All three measurements are the first direct determinations of these BDEs. By combining the BDE of HoO+ with the well-established ionization energy of Ho, the exothermicity of Ho in the title chemi-ionization reaction can also be obtained as 0.00 ± 0.13 eV. All experimental thermochemistry was then compared to quantum chemical calculations for the purpose of establishing benchmarks and validation. BDEs determined via these calculations are in agreement with the experiment within the inherent experimental and theoretical uncertainties, with results obtained at the coupled-cluster with single, double, and perturbative triple excitations, CCSD(T), using all-electron basis sets yielding the most accurate results.
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Affiliation(s)
- Cameron J Owen
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - JungSoo Kim
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - P B Armentrout
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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14
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Kim J, Armentrout PB. Thermochemistry of the Ir + + SO 2 reaction using guided ion beam tandem mass spectrometry and theory. J Chem Phys 2021; 154:124302. [PMID: 33810653 DOI: 10.1063/5.0047513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Kinetic energy dependences of the reactions of Ir+ (5F5) with SO2 were studied using a guided ion beam tandem mass spectrometer and theory. The observed cationic products are IrO+, IrS+, and IrSO+, formed in endothermic reactions. Bond dissociation energies (BDEs) of the products are determined by modeling the kinetic energy dependent product cross sections: D0(Ir+-O) = 4.27 ± 0.11 eV, D0(Ir+-S) = 4.03 ± 0.06 eV, and D0(Ir+-SO) ≥ 2.95 ± 0.06 eV. The oxide BDE agrees well with literature values, whereas the two latter results are novel measurements. Quantum mechanical calculations are performed at the B3LYP level of theory using the def2-TZVPPD basis set for all product BDEs with additional calculations for IrS+, IrO2 +, and IrSO+ at the coupled cluster with single, double, and perturbative triple excitation levels with def2-QZVPPD and aug-cc-pVXZ (X = T and Q and for IrS+, also X = 5) basis sets and complete basis set extrapolations. These theoretical BDEs agree reasonably well with the experimental values. 1A1 (IrO2 +), 5Δ4 (IrS+), and 3A″/1A' (IrSO+) are found to be the ground states after including empirical spin-orbit corrections. The potential energy surfaces including intermediates and transition states for each reaction are also calculated at the B3LYP/def2-TZVPPD level. The formation of MO+ (M = Re, Os, and Ir) from M+ + SO2 reactions is compared with those from the M+ + O2 and M+ + CO reactions, where interesting trends in cross sections are observed. Overall, these studies suggest that the M+ + O2 reactions had restrictions associated with reactions along A' and A″ surfaces.
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Affiliation(s)
- JungSoo Kim
- Department of Chemistry, University of Utah, 315 S 1400 E Rm 2020, Salt Lake City, Utah 84112, USA
| | - P B Armentrout
- Department of Chemistry, University of Utah, 315 S 1400 E Rm 2020, Salt Lake City, Utah 84112, USA
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