Product vibrational distributions in CH3Br photodissociation

Escure, Christelle; Leininger, Thierry; Lepetit, Bruno

doi:10.1016/j.cplett.2009.08.077

Cited by 4 publications

(6 citation statements)

References 38 publications

(86 reference statements)

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“…translational energy acquired by the fragments, as well as vibrational and rotational energy. The vibrational and rotational energy released into the methyl fragment after CH 3 Br photodissociation were investigated both experimentally [9,10] and theoretically [14] for various excitation wavelengths.…”

Section: Pump Pulse Excitationmentioning

confidence: 99%

“…6(a)), and (ii) 0.4 eV of the E AVL is converted into internal vibrational and rotational motion and the rest into kinetic energy (black dashed curve in Fig. 6(a)) [14]. If we consider that the dissociation has occurred in the region where the potential energy reaches a plateau on the repulsive potentials, which corresponds to a Br-CH 3 internuclear distance of about 4.25 Å [11] (cf Fig.…”

Section: Pump Pulse Excitationmentioning

confidence: 99%

“…has higher vibrational energy, when it is formed together with the Br-channel. Although the CH 3 Br A-band absorption is energetically higher and steeper than the CH 3 I A-band, the CH 3 Br should dissociate slower than CH 3 I because a larger amount of the energy available for the dissociation is released into the CH 3 fragment as internal energy, making CH 3 vibrationally hotter when it is produced from CH 3 Br than CH 3 I photodissociation [14].…”

Section: Introductionmentioning

confidence: 99%

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Tracing dissociation dynamics of CH3Br in the 3Q0 state with femtosecond extreme ultraviolet ionization

Vaida¹,

Leone²

2014

Chemical Physics

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The ultrafast photodissociation dynamics of gas phase CH 3 Br molecules in the red wing of the A-band, i.e. the first molecular adsorption continuum, is investigated by pump-probe spectroscopy. The experiment employs femtosecond laser pulses at 266 nm in the ultraviolet to dissociate the molecule and high order harmonic extreme ultraviolet pulses in conjunction with time-of-flight mass spectrometry to ionize and detect the fragments. A dissociation time of 116 ± 25 fs is obtained from the pump-probe risetime of the Br + ion signal, which originates from formation of either or both Br( 2 P 3/2 ) or Br ⁄ ( 2 P 1/2 ). The timescale is in a good agreement with the previously calculated A-band dissociation time of CH 3 Br using the anisotropy parameter b deduced from angular photodissociation experiments. Based on classical molecular dynamics simulations and previous spectroscopic information, the most likely pathway is dissociation of the CH 3 Br molecule via the 3 Q 0 state of the A-band, which correlates with the formation of the spin-orbit excited bromine fragment.

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Section: Pump Pulse Excitationmentioning

confidence: 99%

Section: Pump Pulse Excitationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tracing dissociation dynamics of CH3Br in the 3Q0 state with femtosecond extreme ultraviolet ionization

Vaida¹,

Leone²

2014

Chemical Physics

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“…16 The nonadiabatic transition probability between the 1 Q 1 and 3 Q 0 states was evaluated from the images. Escure et al reported the photodissociation dynamics of CH 3 Br using wave packet propagation technique on coupled ab initio potential energy curves in the Ã-band 3,5 and in Rydberg states using wave packet propagation technique. 4 Regarding CH 3 I, Rubio-Lago et al reported the photodissociation by using a combination of the slice imaging and resonance enhanced multiphoton ionization.…”

Section: (Ch 3 I)mentioning

confidence: 99%

“…Such a great interest in the dissociation of these halides is mainly due to two reasons; one is the benchmark role of this system in studying multichannel dissociation of simple molecules in which the spin-orbit interaction is expected to play a significant role, 1-8 the other is the formation of halogen atoms by the photolysis of these species as a cause of the destruction of ozone in the earth's atmosphere. [9][10][11] Some of these huge experimental and theoretical studies are referred to in recent papers by Townsend et al 2 (CH 3 Cl), Escure et al [3][4][5] and Blanchet et al 12 (CH 3 Br), and Rubio-Lago et al 13 and Alekseyev et al [6][7][8] …”

Section: Introductionmentioning

confidence: 98%

Dissociation mechanisms of excited CH3X (X = Cl, Br, and I) formed via high-energy electron transfer using alkali metal targets

Hayakawa

Tsujinaka

Fujihara

2012

The Journal of Chemical Physics

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High-energy electron transfer dissociation (HE-ETD) on collisions with alkali metal targets (Cs, K, and Na) was investigated for CH(3)X(+) (X = Cl, Br, and I) ions by a charge inversion mass spectrometry. Relative peak intensities of the negative ions formed via HE-ETD strongly depend on the precursor ions and the target alkali metals. The dependency is explained by the exothermicities of the respective dissociation processes. Peak shapes of the negative ions, especially of the X(-) ions, which comprise a triangle and a trapezoid, also strongly depend on the precursor ions and the target alkali metals. The trapezoidal part of the I(-) peak observed with the Na target is more dominant and much broader than that with the Cs target. This dependence on the targets shows an inverse relation between the peak width and the available energy, which corresponds to the exothermicity assuming formation of fragment pair in their ground internal states. From a comparison of the kinetic energy release value calculated from the trapezoidal shape of I(-) with the available energy of the near-resonant level on the CH(3)I potential energy curve reported by ab initio calculations, the trapezoidal part is attributed to the dissociation to CH(3) + I((2)P(3/2)) via the repulsive (3)Q(1) state of CH(3)I, which is not dominant in the photo-dissociation of CH(3)I. The observation of trapezoid shape of the CH(2)I(-) peak with the Cs target indicates spontaneous dissociation via repulsive potential from the (3)R(2) Rydberg state, although the correlation between the (3)R(2) Rydberg state and relevant repulsive states has not been reported by any theoretical calculation.

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Vibrational excitations in chloromethyl radical formed by the photodissociation of chlorobromomethane

Zhu

et al. 2014

The Journal of Chemical Physics

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Using velocity map ion imaging, the photodissociation of chlorobromomethane (CH2BrCl) at 233-234 nm has been studied. The total translational energy distributions and the anisotropy parameters have been determined from the ion images of the photofragments Br ((2)P1/2) (denoted as Br(*)) and Br ((2)P3/2) (denoted as Br) for the dominant CH2BrCl + hv → CH2Cl + Br(*) and CH2BrCl + hv → CH2Cl + Br channels. Using an impulsive model invoking angular momentum conservation, the vibrational energy distributions of the chloromethyl radicals have been derived from the total translational energy distributions for the two channels. The study suggests that there are a number of vibrational modes of the chloromethyl radical to be excited in both of the two photodissociation channels. In the Br* channel, the CH2 s-stretch mode v1 has the most probability of excitation. While in the Br channel, the CH2 scissors mode ν2 is attributed to the highest peak of the vibrational energy curve of the chloromethyl radical. The results further imply that, following absorption of one UV photon of 234 nm, other vibrational modes besides v5 (C-Br stretch mode) are also excited in the parent molecule.

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Product vibrational distributions in CH3Br photodissociation

Cited by 4 publications

References 38 publications

Tracing dissociation dynamics of CH3Br in the 3Q0 state with femtosecond extreme ultraviolet ionization

Tracing dissociation dynamics of CH3Br in the 3Q0 state with femtosecond extreme ultraviolet ionization

Dissociation mechanisms of excited CH3X (X = Cl, Br, and I) formed via high-energy electron transfer using alkali metal targets

Vibrational excitations in chloromethyl radical formed by the photodissociation of chlorobromomethane

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