Gas Phase Photoproduction of Diatomic Metal Nitrides During Metal Nitride Laser Chemical Vapor Deposition

Cheon, Jinwoo; Guile, Matthew; Muraoka, Peter; Zink, Jeffrey I.

doi:10.1021/ic981365b

Cited by 19 publications

(22 citation statements)

References 23 publications

(31 reference statements)

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“…Rabi (19) The evolution of the density matrix under such a driving field is illustrated in Figure 1b. As an approximation, a stepwise change in occupations of two interacting orbitals is adopted.…”

Section: Journal Of Chemical Theory and Computationmentioning

confidence: 99%

“…Luminescence spectroscopy and photoionization time-of-flight (PI-TOF) mass spectrometry have been used to study the photofragmentation of gas-phase metal-containing molecules. − The corresponding computational analysis of these processes, however, is complicated and challenging. The laser field can induce both excitation and de-excitation processes between the electronic states of the target molecule.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Photoinduced Charge Transfer versus Fragmentation Pathways in Lanthanum Cyclopentadienyl Complexes

Han

Meng

Rasulev

et al. 2017

J. Chem. Theory Comput.

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This study compares two competing pathways of photoexcitations in gas-phase metal−organic complexes: first, a sequence of phonon-assisted electronic transitions leading to dissipation of the energy of photoexcitations and, second, a sequence of light-driven electronic transitions leading to photolysis. Phonon-assisted charge carrier dynamics is investigated by combination of the density matrix formalism and on-the-fly nonadiabatic couplings. Light-driven fragmentation is modeled by a time-dependent excited-state molecular-dynamics (TDESMD) algorithm based on Rabi theory and principles similar to the trajectory surface hopping approximation. Numerical results indicate that, under the medium intensity of the laser field, lightdriven electronic transitions are more probable than phonon-assisted ones. The formation of multiple products is observed in TDESMD trajectories. Simulated mass spectra are extracted from TDESMD simulations and compared to experimental photoionization time-of-flight (PI-TOF) mass spectra. It is found that several features in the experimental mass spectra are reproduced by the simulations.

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Section: Journal Of Chemical Theory and Computationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photoinduced Charge Transfer versus Fragmentation Pathways in Lanthanum Cyclopentadienyl Complexes

Han

Meng

Rasulev

et al. 2017

J. Chem. Theory Comput.

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show abstract

“…Experimentally, we and others have demonstrated that photoionization time-of-flight mass spectrometry (PI–TOF–MS) is a powerful tool for investigating the photofragmentation mechanisms of metal–organic precursors. − Theoretical and computational challenges of exploring the combined electronic and nuclear dynamics in the presence of laser field are due to the breakdown of the Born–Oppenheimer approximation . For nonequilibrium states, the dynamics of the nuclei are coupled to the dynamics of the electronic state, going beyond the Born–Oppenheimer approximation, while electronic state dynamics is perturbed by electric field of laser. − The time evolution of coupled electronic and nuclear degrees of freedom can be explored by propagating the elements of the density matrix through the Liouville–von Neumann equation of motion. − Both trajectory surface hopping methods , and self-consistent potential methods , have been used to treat the coupling.…”

Section: Introductionmentioning

confidence: 99%

Photofragmentation of the Gas-Phase Lanthanum Isopropylcyclopentadienyl Complex: Computational Modeling vs Experiment

et al. 2015

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Photofragmentation of the lanthanum isopropylcyclopentadienyl complex, La(iCp), was explored through time-dependent excited-state molecular dynamics (TDESMD), excited-state molecular dynamics (ESMD), and thermal molecular dynamics (MD). Simulated mass spectra were extracted from ab initio molecular dynamics simulations through a new and simple method and compared to experimental photoionization time-of-flight (PI-TOF) mass spectra. The computational results indicate that the value of excitation energy and mechanism of excitation determine the dissociation process.

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“…There have been many studies on the photofragmentation pathways of gas-phase molecular compounds, − metal–organic complexes, − and clusters. , Recently, our group reported the unimolecular gas-phase photodissociation mechanisms of lanthanide tris(η 5 -cyclopentadienyl) complexes, Ln(Cp) 3 , and lanthanide tris(tetramethylcyclopentadienyl) complexes, Ln(TMCp) 3 , through both experimental photoionization time-of-flight mass spectrometry (PI-TOF-MS) and theoretical atomistic simulation of the fragmentation dynamics . It was hypothesized that two types of reaction pathways dominate in the photofragmentation of both Ln(Cp) 3 and Ln(TMCp) 3 precursors: intact ligand stripping, leading to the production of bare metal, and ligand cracking within the metal–ligand complex, giving rise to metal carbide and metal hydrocarbide compounds.…”

Section: Introductionmentioning

confidence: 99%

Photofragmentation Pathways for Gas-Phase Lanthanide Tris(isopropylcyclopentadienyl) Complexes

et al. 2016

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Photofragmentation mechanisms of gas-phase lanthanide tris-(isopropylcyclopentadienyl) complexes, Ln(iCp) 3 , were studied through experimental photoionization time-of-flight mass spectrometry (PI-TOF-MS). A DFTbased time-dependent excited-state molecular dynamics (TDESMD) algorithm, under standard approximations, was used to simulate the photofragmentation process. Two competing reaction pathways, intact ligand stripping and ligand cracking within the metal−ligand complex, were hypothesized based on experimental data. It was evident that intramolecular hydrogen, methyl, and isopropyl abstraction play an important role in the ligand-cracking reaction pathway, leading to metal carbide and metal hydrocarbide products. The TDESMD simulations also produced branching reaction pathways for ligand ejection and ligand cracking and further suggested that both pathways are initiated by ligand-to-metal charge transfer. Although the simulations reproduced several of the proposed reactions and several of the products of cracking observed in the PI-TOF mass spectra, differences between the simulation and experimental results suggest specific directions for improvement in the computational model.

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Gas Phase Photoproduction of Diatomic Metal Nitrides During Metal Nitride Laser Chemical Vapor Deposition

Cited by 19 publications

References 23 publications

Photoinduced Charge Transfer versus Fragmentation Pathways in Lanthanum Cyclopentadienyl Complexes

Photoinduced Charge Transfer versus Fragmentation Pathways in Lanthanum Cyclopentadienyl Complexes

Photofragmentation of the Gas-Phase Lanthanum Isopropylcyclopentadienyl Complex: Computational Modeling vs Experiment

Photofragmentation Pathways for Gas-Phase Lanthanide Tris(isopropylcyclopentadienyl) Complexes

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