Experimental and Theoretical Studies of OD A<sup>2</sup>Σ<sup>+</sup>State Lifetimes and Predissociations

Bergeman, T.; Erman, P.; Haratym, Z.; Larsson, Mats

doi:10.1088/0031-8949/23/1/007

Cited by 38 publications

(12 citation statements)

References 42 publications

(29 reference statements)

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“…For OD, the predissociated levels are as follows: v ‘ = 0, N ‘ > 36; v ‘ = 1, N ‘ > 29; v ‘ = 2, N ‘ > 15; v ‘ = 3, N ‘ > 0. Yarkony 41 performed a theoretical treatment of the predissociation of the individual rovibronic levels and obtained a set of radiative lifetimes τ R and total decay rates τ , in good agreement with the available experimental data. , The effective lifetimes τ are related to the predissociation rates A NR through 1/ τ = 1/τ R + A NR , and thus, the nascent populations, N ‘ , can be obtained from the measured populations, N TSVD , by applying the correction: N ‘ = N TSVD /(1 − τ A NR ) = N TSVD ( τ R / τ ). The rovibrational populations obtained from the measured line intensities by the TSVD method were systematically corrected in this fashion.…”

Section: Resultsmentioning

confidence: 62%

“…These interactions introduce nonradiative decay channels, which compete with the radiative channels and reduce the lifetimes and fluorescence yields of the corresponding levels. Brzozowsky et al and Bergeman et al measured the lifetimes τ of the individual F 1 and F 2 rotational sublevels, characterized by values of j = N ± 1 / 2 , of OH(A 2 Σ + , v ‘ = 0−2) and OD(A 2 Σ + , v ‘ = 0−3), respectively. From these lifetimes, these authors deduced the predissociation rates, A NR , of the levels lying above the dissociation limit.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Photodissociation of H₂O and D₂O in B̃, C̃, and D̃ States (134−119 nm). Comparison between Experiment and ab Initio Calculations

et al. 2001

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Rotational and vibrational state distributions have been measured for the OH/OD(A2Σ+) fragment produced by the photodissociation of H2O/D2O at a set of wavelengths in the 133−119 nm range that lead to excitation of the B̃(1A1) state, either directly or through particular absorption features of the C̃B1 ← X̃1A1 and D̃1A1 ← X̃1A1 Rydberg transitions. The experimental distributions are obtained from the AΣ+−X2Π fluorescence spectra using a truncated single value decomposition method (TSVD). They are compared to distributions calculated in a complete three-dimensional quantum mechanical treatment by using two sets of diabatic potential energy surfaces obtained by Dobbyn and Knowles (DK) and by van Harrevelt and van Hemert (Leiden). The measured vibrational branching ratios seem to be better accounted for by the former and the rotational distributions by the latter. However, a more detailed analysis indicates that the DK surface would presumably account for the experiment if the room-temperature rotational distribution of the parent water molecule were introduced in the calculation. The experimental results are therefore interpreted as a confirmation of the more direct and shorter-lived trajectories favored by the DK surface.

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Section: Resultsmentioning

confidence: 62%

Section: Resultsmentioning

confidence: 99%

Photodissociation of H₂O and D₂O in B̃, C̃, and D̃ States (134−119 nm). Comparison between Experiment and ab Initio Calculations

et al. 2001

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“…The phenomenon of predissociation is illustrated in Figure for the hydroxyl radical, a molecule with a relatively low density of electronic states. , The lower rovibronic levels of the A 2 Σ + state decay by fluorescence to the ground X 2 Π state, but higher levels couple via spin–orbit interaction to the repulsive 4 Σ – and 4 Π states, causing these levels to dissociate to ground state O and H atoms . The result is that rovibronic levels of the A 2 Σ + state, which correlates to the O 1 D + H 2 S separated atom limit, fall apart long before this limit is reached.…”

Section: Predissociationmentioning

confidence: 99%

Section: Predissociationmentioning

confidence: 99%

Predissociation Measurements of Bond Dissociation Energies

Morse

2018

Acc. Chem. Res.

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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...

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“…Use of the high-frequency deflection approach has produced a value of 760 ± 20 ns for OH73 and 755 ± 40 ns for OD. 74 Lifetimes measured by using the LEF approach have resulted in values of 721 ± 5,76 686 ± 14,76 and 693 ± 10 ns.77 Theoretical values78"80 before 1987 are generally in the range 590-636 ns, and thus appear to support the value obtained by using the Hanle effect. This is surprising considering that the more recent LEF measurements are expected to be more accurate.…”

Section: Polyatomic Moleculesmentioning

confidence: 70%

The study of molecular spectroscopy by ab initio methods

Bauschlicher¹,

Langhoff²

1991

Chem. Rev.

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Experimental and Theoretical Studies of OD A²Σ⁺State Lifetimes and Predissociations

Cited by 38 publications

References 42 publications

Photodissociation of H₂O and D₂O in B̃, C̃, and D̃ States (134−119 nm). Comparison between Experiment and ab Initio Calculations

Photodissociation of H₂O and D₂O in B̃, C̃, and D̃ States (134−119 nm). Comparison between Experiment and ab Initio Calculations

Predissociation Measurements of Bond Dissociation Energies

The study of molecular spectroscopy by ab initio methods

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Experimental and Theoretical Studies of OD A2Σ+State Lifetimes and Predissociations

Cited by 38 publications

References 42 publications

Photodissociation of H2O and D2O in B̃, C̃, and D̃ States (134−119 nm). Comparison between Experiment and ab Initio Calculations

Photodissociation of H2O and D2O in B̃, C̃, and D̃ States (134−119 nm). Comparison between Experiment and ab Initio Calculations

Predissociation Measurements of Bond Dissociation Energies

The study of molecular spectroscopy by ab initio methods

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Experimental and Theoretical Studies of OD A²Σ⁺State Lifetimes and Predissociations

Photodissociation of H₂O and D₂O in B̃, C̃, and D̃ States (134−119 nm). Comparison between Experiment and ab Initio Calculations

Photodissociation of H₂O and D₂O in B̃, C̃, and D̃ States (134−119 nm). Comparison between Experiment and ab Initio Calculations