Spectroscopic constants and potential energy curves of yttrium carbide (YC)

Suo, Bingbing; Balasubramanian, K.

doi:10.1063/1.2743015

Cited by 6 publications

(1 citation statement)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: Predissociationmentioning

confidence: 99%

Predissociation Measurements of Bond Dissociation Energies

Morse

2018

Acc. Chem. Res.

View full text Add to dashboard Cite

CONSPECTUS: A fundamental need in chemistry is understanding the chemical bond, for which the most quantitative measure is the bond dissociation energy (BDE). While BDEs of chemical bonds formed from the lighter main group elements are generally well-known and readily calculated by modern computational chemistry, chemical bonds involving the transition metals, lanthanides, and actinides remain computationally extremely challenging. This is due to the simultaneous importance of electron correlation, spin−orbit interaction, and other relativistic effects, coupled with the large numbers of low-lying states that are accessible in systems with open d or f subshells. The development of efficient and accurate computational methods for these species is currently a major focus of the field. An obstacle to this effort has been the scarcity of highly precise benchmarks for the BDEs of M−X bonds. For most of the transition metal, lanthanide, or actinide systems, tabulated BDEs of M−X bonds have been determined by Knudsen effusion mass spectrometric measurements of high-temperature equilibria. The measured ion signals are converted to pressures and activities of the species involved in the equilibrium, and the equilibrium constants are then analyzed using a van't Hoff plot or the third-law method to extract the reaction enthalpy, which is extrapolated to 0 K to obtain the BDE. This procedure introduces errors at every step and ultimately leads to BDEs that are typically uncertain by 2−20 kcal mol −1 (0.1−1 eV). A second method in common use employs a thermochemical cycle in which the ionization energies of the MX molecule and M atom are combined with the BDE of the M + −X bond, obtained via guided ion beam mass spectrometry, to yield the BDE of the neutral, M−X. When accurate values of all three components of the cycle are available, this method yields good resultsbut only rarely are all three values available. We have recently implemented a new method for the precise measurement of BDEs in molecules with large densities of electronic states that is based on the rapid predissociation of these species as soon as the ground separated atom limit is exceeded. When a sharp predissociation threshold is observed, its value directly provides the BDE of the system. With this method, we are able in favorable cases to determine M−X BDEs to an accuracy of ∼0.1 kcal mol −1 (0.004 eV). The method is generally applicable to species that have a high density of states at the ground separated atom limit and has been used to measure the BDEs of more than 50 transition metal−main group MX molecules thus far. In addition, a number of metal−metal BDEs have also been measured with this method. There are good prospects for the extension of the method to polyatomic systems and to lanthanide and actinide-containing molecules. These precise BDE measurements provide chemical trends for the BDEs across the transition metal series, as well as crucial benchmarks for the development of efficient and accurate computational methods for the d-and f-block elem...

show abstract

Section: Predissociationmentioning

confidence: 99%

Predissociation Measurements of Bond Dissociation Energies

Morse

2018

Acc. Chem. Res.

View full text Add to dashboard Cite

show abstract

Electronic structure and bonding characters of the two lowest states of copper, silver, and gold monocarbides

Zhang

Meng

et al. 2011

Computational and Theoretical Chemistry

View full text Add to dashboard Cite

Electronically excited-state properties and predissociation mechanisms of phosphorus monofluoride: A theoretical study including spin–orbit coupling

Bian

2012

The Journal of Chemical Physics

View full text Add to dashboard Cite

The 51 Ω states generated from the 22 Λ - S states of phosphors monofluoride have been investigated using the valence internally contracted multireference configuration interaction method with the Davidson correction and the entirely uncontracted aug-cc-pV5Z basis set. The spin-orbit coupling is computed using the state interaction approach with the Breit-Pauli Hamiltonian. Based on the calculated potential energy curves, the spectroscopic constants of the bound and quasibound Λ - S and Ω states are obtained, and very good agreement with experiment is achieved. Several quasibound states caused by avoided crossings are found. Various curve crossings and avoided crossings are revealed, and with the help of our computed spin-orbit coupling matrix elements, the predissociation mechanisms of the a(1)Δ, b(1)Σ(+), e(3)Π, g(1)Π, and (3)(3)Π states are analyzed. The intricate couplings among different electronic states are investigated. We propose that the avoided crossing between the A(3)Π(0 +) and b(1)Σ(0+) (+) states may be responsible for the fact that the A(3)Π ν' ≥ 12 vibrational levels can not be observed in experiment. The transition properties of the A(3)Π - X(3)Σ(-) transition are studied, and our computed Franck-Condon factors and radiative lifetimes match the experimental results very well.

show abstract

Spectroscopic constants and potential energy curves of yttrium carbide (YC)

Cited by 6 publications

References 54 publications

Predissociation Measurements of Bond Dissociation Energies

Predissociation Measurements of Bond Dissociation Energies

Electronic structure and bonding characters of the two lowest states of copper, silver, and gold monocarbides

Electronically excited-state properties and predissociation mechanisms of phosphorus monofluoride: A theoretical study including spin–orbit coupling

Contact Info

Product

Resources

About