Kinematic constraints on the final state interaction in photodissociation processes

Chen, Kuo-mei; Pei, Cheng-chih

doi:10.1016/0009-2614(87)80900-4

Cited by 13 publications

(6 citation statements)

References 13 publications

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“…The NO formation at some stage of NM decomposition was inferred by several authors. , From our data we can conclude that if NO is formed at all, it is formed in the ground state. Otherwise, we would have detected the characteristic emission below 390 nm. − …”

Section: Discussionmentioning

confidence: 95%

“…Otherwise, we would have detected the characteristic emission below 390 nm. [46][47][48] By comparing neat and sensitized NM spectra and kinetics, we can draw some conclusions about reaction mechanisms. As shown previously, not only is the sensitivity of NM affected by addition of amines 10-14 but the initiation stage seems to be different as well.…”

Section: Discussionmentioning

confidence: 99%

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Emission and Fluorescence Spectroscopy To Examine Shock-Induced Decomposition in Nitromethane

Gruzdkov

Gupta

1998

J. Phys. Chem. A

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Time-resolved emission spectra were obtained from neat and ethylenediamine-sensitized nitromethane shocked to 12-17 GPa peak pressures using step wave loading. Broadband emission identified as chemiluminescence from nitrogen dioxide was observed due to reactions in both neat and amine-sensitized nitromethane. When laser light at 514 nm was present, fluorescence in addition to chemiluminescence was observed in shocked nitromethane-ethylenediamine mixtures; no such fluorescence was found in neat nitromethane. The fluorescing species are assigned to an intermediate formed in the first stage of decomposition in nitromethaneethylenediamine mixtures. The same intermediate was detected previously using time-resolved optical absorption spectroscopy (J. Phys. Chem. A 1998Chem. A , 102, 2322 and was inferred to be a radical anion of nitromethane, CH 3 NO 2 •-. This interpretation is consistent with the fluorescence data reported here. Laser irradiation (∼10 MW/cm 2 at 514 nm) during shock loading resulted in more intense chemiluminescence in both neat nitromethane and nitromethane-ethylenediamine mixtures. However, the effect was qualitatively different in the two cases, and the difference is attributed to different decomposition mechanisms operative initially in neat and sensitized nitromethane.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Emission and Fluorescence Spectroscopy To Examine Shock-Induced Decomposition in Nitromethane

Gruzdkov

Gupta

1998

J. Phys. Chem. A

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“…10 Since then, numerous photodissociation studies of NO 2 in the first absorption band have been carried out. [11][12][13][14][15][16][17][18][19][20][21][22][23][24] In the 1990s, the experiments were mainly performed at a single photolysis wavelength of 355 nm. [11][12][13][14][15][16][17] In these studies, the angular distribution for O( 3 P 2 ) at 355 nm was described by the anisotropy parameter of b = 1.2 AE 0.3, 16 and the lifetime of NO 2 (1 2 B 2 ) state was estimated to be B250 fs.…”

Section: Introductionmentioning

confidence: 99%

“…But, at higher excess energies, where the dissociation becomes more rapid, such models cease to be valid. [20][21][22][23][24] Compared to the first absorption band, the second absorption band starting from B250 nm shows a much simpler vibrational structure, which has a broad maximum at B217 nm. 6 Theoretical calculations 4 clearly verified that this UV band is due to excitation of the 2 2 B 2 state (commonly termed the D ˜2B 2 state).…”

Section: Introductionmentioning

confidence: 99%

Slice imaging study of NO₂ photodissociation via the 1²B₂ and 2²B₂ states: the NO(X²Π) + O(³P_J) product channel

Zhang

Yang

Liu

et al. 2023

Phys. Chem. Chem. Phys.

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“…The unimolecular reaction of NO 2 has been studied extensively over the past 20 years, − ,,,− and it is not the purpose of this article to provide an exhaustive review of these thorough and detailed investigations. Rather, we concentrate on experimental manifestations of overlapping resonances and their relation to statistical descriptions of the unimolecular reaction.…”

Section: Introductionmentioning

confidence: 99%

Unimolecular Reaction of NO₂: Overlapping Resonances, Fluctuations, and the Transition State

Reid

Reisler

1996

J. Phys. Chem.

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The unimolecular decomposition of expansion-cooled NO 2 at excess energies 0-3000 cm -1 is described with emphasis on the manifestations of overlapping resonances. When NO 2 is excited to energies above dissociation threshold, overlapping resonances interfere and give rise to final state-selected spectra which depend on the monitored final state of the NO product. The differences among the spectra diminish with the degree of incoherent superposition (e.g., thermal averaging). In this article, we describe the experimental manifestations of overlapping resonances in the case of barrierless unimolecular reactions and how they relate to transition state theories. We treat the unimolecular reaction of NO 2 using resonance scattering theory combined with random matrix formalism and distinguish between the near-threshold region where the transition state is loose and dissociation at higher excess energies where the transition state has tightened significantly. The final state-selected spectra and their dependence on the degree of resonance overlap are simulated in a qualitative way. Experimentally, fluctuations are observed in the line shapes, positions, and intensities in the spectra; the rotational and vibrational NO state distributions; the spin-orbit states of the oxygen atom correlated with specific quantum states of NO; and the state-specific rates. We show how the patterns of fluctuations in the rotational distributions allow the distinction between the loose and tight transition state cases and discuss the evolution of the excited complex from transition state to final products. In spite of the fluctuations, the averaged results agree well with the predictions of statistical theories, and implications for the transition state and the adiabatic evolution of the NO degrees of freedom are discussed. Even when the product state distributions agree with the predictions of specific statistical models, caution should be exercised in inferring properties of the transition state, due to the unaccounted influence of final state interactions beyond the transition state.

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Kinematic constraints on the final state interaction in photodissociation processes

Cited by 13 publications

References 13 publications

Emission and Fluorescence Spectroscopy To Examine Shock-Induced Decomposition in Nitromethane

Emission and Fluorescence Spectroscopy To Examine Shock-Induced Decomposition in Nitromethane

Slice imaging study of NO₂ photodissociation via the 1²B₂ and 2²B₂ states: the NO(X²Π) + O(³P_J) product channel

Unimolecular Reaction of NO₂: Overlapping Resonances, Fluctuations, and the Transition State

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Kinematic constraints on the final state interaction in photodissociation processes

Cited by 13 publications

References 13 publications

Emission and Fluorescence Spectroscopy To Examine Shock-Induced Decomposition in Nitromethane

Emission and Fluorescence Spectroscopy To Examine Shock-Induced Decomposition in Nitromethane

Slice imaging study of NO2 photodissociation via the 12B2 and 22B2 states: the NO(X2Π) + O(3PJ) product channel

Unimolecular Reaction of NO2: Overlapping Resonances, Fluctuations, and the Transition State

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Slice imaging study of NO₂ photodissociation via the 1²B₂ and 2²B₂ states: the NO(X²Π) + O(³P_J) product channel

Unimolecular Reaction of NO₂: Overlapping Resonances, Fluctuations, and the Transition State