Threshold Ionization Spectroscopy and Theoretical Calculations of LnO (Ln = La and Ce)

Cao, Wenjin; Zhang, Yuchen; Wu, Lu; Yang, Dong‐Sheng

doi:10.1021/acs.jpca.1c00533

Cited by 11 publications

(7 citation statements)

References 58 publications

(124 reference statements)

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“…After the interaction of plume species with the laser beam, gas phase reactions via scattering are the dominant chemical processes in the plasma plume and it should be possible to differentiate between non-reactive and reactive scattering processes depending on the reactivity of the background gas species. The dissociation energy of LaO + ( m = 154) with E diss = 8.57 eV [ 20 ] is larger than that of O 2 , and therefore stable LaO molecules and LaO + ions can be formed additionally by reactions in the plume at a higher O 2 background pressure. On the other hand, MnO + and CaO + have a smaller dissociation energy than O 2 (2.9 eV; 4.1 eV < 5.12 eV) [ 21 ], and their formation at a higher O 2 background pressure is not favoured due to a dissociation via an enhanced scattering rate.…”

Section: Resultsmentioning

confidence: 99%

New Insight into the Gas Phase Reaction Dynamics in Pulsed Laser Deposition of Multi-Elemental Oxides

et al. 2022

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The gas-phase reaction dynamics and kinetics in a laser induced plasma are very much dependent on the interactions of the evaporated target material and the background gas. For metal (M) and metal–oxygen (MO) species ablated in an Ar and O2 background, the expansion dynamics in O2 are similar to the expansion dynamics in Ar for M+ ions with an MO+ dissociation energy smaller than O2. This is different for metal ions with an MO+ dissociation energy larger than for O2. This study shows that the plume expansion in O2 differentiates itself from the expansion in Ar due to the formation of MO+ species. It also shows that at a high oxygen background pressure, the preferred kinetic energy range to form MO species as a result of chemical reactions in an expanding plasma, is up to 5 eV.

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Section: Resultsmentioning

confidence: 99%

New Insight into the Gas Phase Reaction Dynamics in Pulsed Laser Deposition of Multi-Elemental Oxides

et al. 2022

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“…In the case of the initial state reactions, the ionization laser was set at 230 nm for both La and Ce, which is above the ionization energies of the metal oxides and complexes. 46 All reactions were carried out with the same ablation laser power, ligand concentration, and carrier gas pressure in the reservoir. The positive signal of the product ions in the difference spectra indicates an increased formation of the excited state relative to the initial states.…”

Section: Resultsmentioning

confidence: 99%

“…LaO could be formed by the reaction of La atoms with oxygen present in the carrier gas as an impurity or by the laser vaporization of La oxide impurity in the La rod. LaO is ionized by single-photon ionization as the laser energy (230 nm or 43 478 cm −1 ) is above the LaO IE (42 300 cm −1 ), 46 while La could be generated by nonresonant two-photon ionization [IE(La) = 44 980 cm −1 ].…”

Section: Resultsmentioning

confidence: 99%

“…The reactions with the initial state atoms [La: 5d6s 2 ( 2 D 3/2 ), Ce: 4f5d6s 2 ( 1 G 4 ° )] were carried out without the presence of the excitation laser, while those with the excited states La*[5d 2 ( 3 F)6p ( 4 G 5/2 )], Ce*[4f5d( 3 F°)6s6p( 3 P°) ( 5 H 5 )] were performed by fixing the excitation laser at 15 282 cm –1 for La and at 14 244 cm –1 for Ce. In the case of the initial state reactions, the ionization laser was set at 230 nm for both La and Ce, which is above the ionization energies of the metal oxides and complexes . All reactions were carried out with the same ablation laser power, ligand concentration, and carrier gas pressure in the reservoir.…”

Section: Resultsmentioning

confidence: 99%

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Probing La and Ce Excited-State Reactivity with Resonant Two-Photon Ionization Spectroscopy

2022

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Dehydrogenation and C−C bond cleavage of 1-butyne by the excited states of La and Ce atoms are investigated in laser-ablation metal molecular beams. The excited states of the metal atoms are prepared by resonant excitation, detected by resonant two-photon ionization spectroscopy, and the reaction products are monitored by photoionization time-of-flight mass spectrometry. The reactivities of La* [5d 2 ( 3 F)6p ( 4 G 5/2 °)] and Ce* [4f5d( 3 F°)6s6p( 3 P°) ( 5 H 5 )]excited states are observed to be higher than those of the initial states of the corresponding metal atoms. The higher reactivities of the excited states are attributed to their higher energies and favorable electron configurations to form two covalent bonds of the metal-insertion intermediates. Although both excited La and Ce atoms show increased reactivities, the enhancement for Ce is much more pronounced than that of La, which cannot be explained by electron configurations alone. The larger reactivity enhancement from the initial states to the excited state of the Ce atom than that of La is due to the longer lifetime of the Ce excited state.

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“…While there is a substantial body of electronic, vibrational, and rotational spectroscopies of the LnO diatomics, − ,, the study of gas-phase Ln x O y polyatomics has been more limited. Vibrational predissociation spectroscopy of Ce x O y + clusters showed the evolution of structure with size and oxidation.…”

Section: Introductionmentioning

confidence: 99%

Lanthanide Oxides: From Diatomics to High-Spin, Strongly Correlated Homo- and Heterometallic Clusters

2021

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Small lanthanide (Ln) oxide clusters present both experimental and theoretical challenges because of their partially filled, core-like 4f n orbitals, a feature that results in a plethora of close-lying and fundamentally similar electronic states. These clusters provide a bottom-up approach toward understanding the electronic structure of defective or doped bulk material but also can offer a challenge to the theorists to find a method robust enough to capture electronic structure patterns that emerge from within the 4f n (0 < n < 14) series. In this Feature Article, we explore the electronic structures of small lanthanide oxide clusters that deviate from bulk stoichiometry using anion photoelectron spectroscopy and supporting density functional theory calculations. We will describe the evolution of electronic structure with oxidation and how Ln x O y − cluster reactivities can be correlated with specific Ln-local orbital occupancies. These strongly correlated systems offer additional insights into how interactions between electrons and electronically complex neutrals can lead to detachment transitions that lie outside of the sudden one-electron detachment approximation generally assumed in anion photoelectron spectroscopy. With a better understanding of how we can control nominally forbidden transitions to sample an array of spin states, we suggest that more in-depth studies on the magnetic states of these systems can be explored. Extending these studies to other Ln-based materials with hidden magnetic phases, along with sequentially ligated single molecule magnets, could advance current understanding of these systems.

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Threshold Ionization Spectroscopy and Theoretical Calculations of LnO (Ln = La and Ce)

Cited by 11 publications

References 58 publications

New Insight into the Gas Phase Reaction Dynamics in Pulsed Laser Deposition of Multi-Elemental Oxides

New Insight into the Gas Phase Reaction Dynamics in Pulsed Laser Deposition of Multi-Elemental Oxides

Probing La and Ce Excited-State Reactivity with Resonant Two-Photon Ionization Spectroscopy

Lanthanide Oxides: From Diatomics to High-Spin, Strongly Correlated Homo- and Heterometallic Clusters

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