Energy transfer of highly vibrationally excited azulene. II. Photodissociation of azulene-Kr van der Waals clusters at 248 and 266nm

Hsu, Hsu Chen; Liu, Chenlin; Lyu, Jia-Jia; Ni, Chi-Kung

doi:10.1063/1.2178296

Cited by 9 publications

(2 citation statements)

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“…In recent years, studies of energy transfer processes have focused, in particular, on understanding the energy transfer probability distribution function, P ( E , E ‘). − This function describes the probability that a molecule initially at energy E ‘ will, following a single collision event, have an energy E . A great deal of effort in energy transfer studies has also been expended to understand the role of “supercollisions”, − events in which a large amount of energy is transferred is a single collision, in relaxation processes.…”

Section: Introductionmentioning

confidence: 99%

Competition between Photochemistry and Energy Transfer in UV-Excited Diazabenzenes. 4. UV Photodissociation of 2,3-, 2,5-, and 2,6-Dimethylpyrazine

et al. 2007

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The quantum yield for HCN formation via 248 nm photodissociation of 2,3-, 2,5-, and 2,6-dimethylpyrazine (DMP, C6N2H8) was measured using diode laser probing of the HCN photoproduct. The total quantum yield is phi = 0.039 +/- 0.07, 0.14 +/- 0.02, and 0.30 +/- 0.06 for 248 nm excitation of 2,3-, 2,5- and 2,6-DMP, respectively. Analysis of the quenching data within the context of a gas kinetic, strong collision model allows an estimate of the rate constant for HCN production via DMP photodissociation, ks = 4.1 x 10(3), 1.0 x 10(3), and 1.3 x 10(4) s(-1) for 2,3-, 2,5- and 2,6-DMP, respectively. Unlike HCN produced from the photodissociation of pyrazine and methylpyrazine, the amount of HCN produced via a prompt, unquenched dissociation channel was essentially zero, suggesting little multiphoton UV absorption. The rate constants for HCN formation together with previously measured rate constants for HCN production from photodissociation of pyrazine and methylpyrazine have been used to investigate possible reaction mechanisms. The position of the methyl group affects the HCN rate constant, suggesting that the mechanism for pyrazine dissociation involves an initial step that is hindered by the addition of the methyl groups. The proposed initial molecular motion of the mechanism, an out-of-plane H atom migration across a N atom, is consistent with (1) the position of the methyl groups, (2) the dissociation lifetime of the various pyrazine molecules studied, and (3) the observed large energy transfer magnitudes from pyrazine near dissociation. These so-called "supercollisions" have been linked to low-frequency, out-of-plane motion, suggesting that the molecular motions leading to efficient energy transfer are the same motions involved in dissociation. In addition, the pyrazine (C4N2H4) 248 nm photoproduct (C3H3N) was identified as acrylonitrile using IR spectroscopy, an observation that aids in understanding the dissociation mechanism.

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Section: Introductionmentioning

confidence: 99%

Competition between Photochemistry and Energy Transfer in UV-Excited Diazabenzenes. 4. UV Photodissociation of 2,3-, 2,5-, and 2,6-Dimethylpyrazine

et al. 2007

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“…We were unable to detect any trace of van der Waals clusters such as azulene-N 2 or (azulene) n in the mass spectrum under these expansion conditions. 16,17 For each pump-probe delay, the ion signal was averaged over ~2000 laser pulses and the photoelectron image over ~4×10 5 laser pulses. The images were calibrated by recording photoelectron signals from nitric oxide, acetylene and oxygen at various accelerating and focussing voltages.…”

mentioning

confidence: 99%

Time-dependent photoionization of azulene: Competition between ionization and relaxation in highly excited states

Blanchet

Raffael

Turri

et al. 2008

The Journal of Chemical Physics

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Pump-probe photoionization has been used to map the relaxation processes taking place from highly vibrationally excited levels of the S 2 state of azulene, populated directly or via internal conversion from the S 4 state. Photoelectron spectra obtained by 1+2' two-color time-resolved photoelectron imaging are invariant (apart from in intensity) to the pump-probe time delay and to pump wavelength. This reveals a photoionization process which is driven by an unstable electronic state (e.g. doubly excited state) lying below the ionization potential. This state is postulated to be populated by a probe transition from S 2 and to rapidly relax via an Auger like process onto highly vibrationally excited Rydberg states. This accounts for the time invariance of the photoelectron spectrum. The intensity of the photoelectron spectrum is proportional to the population in S 2 . An exponential energy gap law is used to describe the internal conversion rate from S 2 to S 0 . The vibronic coupling strength is found to be larger than 60±5 µeV.

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Experiments on collisional energy transfer

King

Barker

2019

Unimolecular Kinetics - Parts 2 and 3: Collisional Energy Transfer and the Master Equation

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Energy transfer of highly vibrationally excited azulene. II. Photodissociation of azulene-Kr van der Waals clusters at 248 and 266nm

Cited by 9 publications

References 43 publications

Competition between Photochemistry and Energy Transfer in UV-Excited Diazabenzenes. 4. UV Photodissociation of 2,3-, 2,5-, and 2,6-Dimethylpyrazine

Competition between Photochemistry and Energy Transfer in UV-Excited Diazabenzenes. 4. UV Photodissociation of 2,3-, 2,5-, and 2,6-Dimethylpyrazine

Time-dependent photoionization of azulene: Competition between ionization and relaxation in highly excited states

Experiments on collisional energy transfer

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