Photo induced three body decay

Maul, C.; Gericke, Karl‐Heinz

doi:10.1080/014423597230307

Cited by 111 publications

(72 citation statements)

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“…This cluster of points is therefore consistent with concerted dissociation from a nearly linear configuration of IIBr − , in which both bonds break on the time scale of vibrational motion in the anion. 61 This mechanism appears to hold for channels 3A and 3B.…”

Section: Three-body Dissociationmentioning

confidence: 93%

Two- and three-body photodissociation dynamics of diiodobromide (I2Br−) anion

Crider

Harrison

Neumark

2011

The Journal of Chemical Physics

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The photodissociation of gas-phase I(2)Br(-) was investigated using fast beam photofragment translational spectroscopy. Anions were photodissociated from 300 to 270 nm (4.13-4.59 eV) and the recoiling photofragments were detected in coincidence by a time- and position-sensitive detector. Both two- and three-body channels were observed throughout the energy range probed. Analysis of the two-body dissociation showed evidence for four distinct channels: Br(-) + I(2), I(-) + IBr, Br+I(2) (-), and I + IBr(-). In three-body dissociation, Br((2)P(3∕2)) + I((2)P(3∕2)) + I(-) and Br(-) + I((2)P(3∕2)) + I((2)P(3∕2)) were produced primarily from a concerted decay mechanism. A sequential decay mechanism was also observed and attributed to Br(-)((1)S)+I(2)(B(3)Π(0u) (+)) followed by predissociation of I(2)(B).

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Section: Three-body Dissociationmentioning

confidence: 93%

Two- and three-body photodissociation dynamics of diiodobromide (I2Br−) anion

Crider

Harrison

Neumark

2011

The Journal of Chemical Physics

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“…Maul and Gericke in their review paper of the molecular three-body breakup distinguished several different dissociation mechanisms, and one such process is termed sequential [60]. In the case of the CH 3 + H + H channel this can be described by…”

Section: Resultsmentioning

confidence: 99%

“…* molecule is created in a highly excited state, which subsequently decays into CH 3 + H. The kinetic energy of the hydrogen atom ejected at the first step relates to the internal excitation of the intermediate CH 4 and its maximum value of M CH 4 /M CH 5 E k corresponds to the case when internal energy of CH 4 is comparable to the dissociation energy into CH 3 + H. If the intermediate molecule remains intact for a time longer than 10 −11 s, (i.e., for longer than a rotational period), the second bond rupture will be independent of the first [60]. During this time the free hydrogen atom will move a sufficient distance away from the CH 4 molecule, preventing any interaction between them.…”

Section: Resultsmentioning

confidence: 99%

Dissociative recombination of CH5+and CD5+:

et al. 2010

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The dissociative recombination (DR) of CH 5 + and CD 5 + has been studied at the heavy-ion storage ring CRYRING. The fragmentation dynamics of the dominant reaction channel CH 3 + H + H has been investigated using an imaging detector. The results indicate that a two-step process via the production of a CH 4 intermediate, which has sufficient energy to fragment further to CH 3 + H, may play an important role. Discrepancies between the present and earlier results obtained from storage ring measurements with those from flowing afterglow experiments are addressed. Newly measured branching fractions in the DR of CD 5 + show an excellent agreement with branching fractions previously measured for CH 5 + , and the absolute DR cross sections have been also measured over an interaction energy range between ∼0 and 0.1 eV for both isotopologs.

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“…[1] Three-body dissociation can be classified into synchronous concerted, asynchronous concerted, and sequential (or stepwise) decay processes with criterions of (t 2 Àt 1 )/t rot = 0, 1, and > 1, respectively; [1] t rot denotes the rotational period of fragment AB. Most three-body fragmentations belong to sequential processes but fewer are best described as concerted.…”

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confidence: 99%

Evidence for Synchronous Concerted Three-Body Dissociation of Propenal to C2H2+CO+H2

2011

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Due to intriguing dynamics, three-body (or triple) photodissociation ABC + hn t 0 !ABC* t 1 !AB* + C t 2 !A + B + C has received attention for decades.[1] Three-body dissociation can be classified into synchronous concerted, asynchronous concerted, and sequential (or stepwise) decay processes with criterions of (t 2 Àt 1 )/t rot = 0, 1, and > 1, respectively;[1] t rot denotes the rotational period of fragment AB. Most three-body fragmentations belong to sequential processes but fewer are best described as concerted. Based on Rice-Ramsperger-Kassel-Marcus (RRKM) theory, in principle a large excitation energy might shorten the decay time and thus lead to three-body dissociation in an asynchronous concerted process. More product channels, however, become accessible with large excitation energy, which complicates experiments and diminishes the individual branching ratios to each dissociation pathway. Synchronous concerted dissociation typically occurs on reactions A 2 B!2 A + B and A 3 !3 A by breaking two or three equivalent chemical bonds; for instance C 2 H 2 N 4 (sym-tetrazine)!2 HCN + N 2 , [2][3][4] C 2 H 2 O 2 (glyoxal)!2 CO + H 2 , [5][6][7] and C 3 H 3 N 3 (sym-triazine)! 3 HCN. [8][9][10] The three dissociating systems have barrier heights of merely 47 kcal mol À1 , [2] 59 kcal mol À1 , [7] and 81 kcal mol À1 , [9] respectively; these values are smaller or comparable with that of typical two-body dissociation. Dissociation to three different types of molecular fragments by breaking three nonequivalent chemical bonds had not been observed as a synchronous concerted process before the present work. Propenal (acrolein, CH 2 =CHÀCH=O) has both carbonyl and olefinic chromophors. Photodissociation dynamics of propenal were investigated using optical excitation to state np* in a wavelength range of 300-334 nm [11][12][13] and to state pp* at wavelengths of 193 nm and 200 nm. [14][15][16][17][18][19][20] Dissociation to C 2 H 3 + HCO, CH 2 CHCO + H, and C 2 H 4 + CO are three primary pathways of propenal optically excited to the np* state. Fang [21] computed the potential energy surfaces of propenal governing the three primary dissociations in the ground electronic state and in the lowest-lying singlet and triplet electronic excited states using quantum chemical calculations. More product channels open and secondary dissociation becomes more significant as the optical excitation energy increases. However, the previous experiments [14][15][16][17][18][19][20] with optical excitation at 193 nm and 200 nm were devoted only to the three major channels C 2 H 3 + HCO, CH 2 CHCO + H, and C 2 H 4 + CO; distributions of translational and internal energies of products were interrogated. Three-body photodissociation of propenal has never been taken into account in experiments and calculations before our work. Herein, we observed the synchronous concerted three-body dissociation of propenal to C 2 H 2 + CO + H 2 upon photoexcitation at 193 nm using photofragment translational spectroscopy and characterized the corresponding tr...

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Photo induced three body decay

Cited by 111 publications

References 0 publications

Two- and three-body photodissociation dynamics of diiodobromide (I2Br−) anion

Two- and three-body photodissociation dynamics of diiodobromide (I2Br−) anion

Dissociative recombination of CH5+and CD5+:

Evidence for Synchronous Concerted Three-Body Dissociation of Propenal to C2H2+CO+H2

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