Photoelectron Spectra of Some Bromoethylenes and 2-Bromopropene

Chadwick, David; Frost, D. C.; Katrib, A.; McDowell, C. A.; McLean, R. A. N.

doi:10.1139/v72-423

Cited by 41 publications

(15 citation statements)

References 20 publications

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“…2a shows the first ionic band. In agreement with previous results [4][5][6], three ionic vibrational modes can be easily deduced from the observed structure (Table 5). The first progression corresponds to v 9 (CH 2 rocking) with a value of ṽ 9 = 380 ± 30 cm -1 .…”

Section: Computational Resultssupporting

confidence: 92%

“…The observed vertical ionization energies are displayed in Table 1. The present measurements agree with those reported earlier [4][5][6]8].…”

Section: The He(i)-photoelectron Spectrasupporting

confidence: 94%

“…The He(I)-photoelectron spectrum of C 2 H 3 Br at medium resolution has been investigated by several authors [4][5][6]. A low resolution threshold-photoelectron spectrum has been reported by Lohr et al [7].…”

Section: Introductionmentioning

confidence: 99%

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Photoelectron spectroscopy of vinylbromide and intramolecular dynamics of the ionic B̃ state

et al. 2000

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In this paper, we report the He(I) photoelectron spectrum (PES) and the threshold-photoelectron (TPES) spectrum of C 2 H 3 Br. The fine structure observed in the first two ionic states in the He(I) spectrum is assigned to progressions belonging partially to previously unobserved vibrational normal modes. The TPES has been measured between 9.0 and 25.0 eV, and the photon energy range of 9.8-12.0 eV has been investigated in more detail. Extensive calculations with the GAUSSIAN set of programs have been performed to help in the assignment of the observed features. Furthermore, a conical intersection between the Ã 2 A" and the 2 A" states was found to take place along the C-Br stretching coordinate. Intramolecular dynamics of the 2 A" state, initially prepared in the Frank-Condon region, was probed by the Fourier transform of the spectrum. The 2 A" state is almost readily depleted, most probably due to a very effective internal conversion through the conical intersection.

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Section: Computational Resultssupporting

confidence: 92%

“…The observed vertical ionization energies are displayed in Table 1. The present measurements agree with those reported earlier [4][5][6]8].…”

Section: The He(i)-photoelectron Spectrasupporting

confidence: 94%

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Photoelectron spectroscopy of vinylbromide and intramolecular dynamics of the ionic B̃ state

et al. 2000

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“…In Fig. 2 (100), (AIE (adiabatic ionization energy) = 9.82 eV) 39 and isopropenyl bromide (m/z = 121, AIE = 9.58 eV), 40 non-deuterated for both CH and CD experiments. 3.3.1.…”

Section: Acetone Photodissociationmentioning

confidence: 99%

Formation of dimethylketene and methacrolein by reaction of the CH radical with acetone

Goulay

Derakhshan

Maher

et al. 2013

Phys. Chem. Chem. Phys.

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. (2013). Formation of dimethylketene and methacrolein by reaction of the CH radical with acetone. Physical Chemistry Chemical Physics, 15 (11), 4049-4058. Formation of dimethylketene and methacrolein by reaction of the CH radical with acetone AbstractThe reaction of the methylidyne radical (CH) with acetone ((CH3)2CO) is studied at room temperature and at a pressure of 4 Torr (533.3 Pa) using a multiplexed photoionization mass spectrometer coupled to the tunable vacuum ultraviolet synchrotron radiation of the Advanced Light Source at Lawrence Berkeley National Laboratory. The CH radicals are generated by 248 nm multiphoton photolysis of bromoform and react with acetone in an excess of helium and nitrogen gas flow. The main observed reaction exit channel is elimination of a hydrogen atom to form C4H6O isomers. Analysis of photoionization spectra identifies dimethylketene and methacrolein as the only H-elimination products. The best fit to the data gives branching ratios of 0.68 ± 0.14 for methacrolein and 0.32 ± 0.07 for dimethylketene. A methylketene spectrum measured here is used to reanalyze the photoionization spectrum obtained at m/z = 56 for the CH + acetaldehyde reaction, (Goulay et al., J. Phys. Chem. A, 2012, 116, 6091) yielding new H-loss branching ratios of 0.61 ± 0.12 for acrolein and 0.39 ± 0.08 for methylketene. The contribution from methyleneoxirane to the reaction product distribution is revised to be negligible. Coupled with additional product detection for the CD + acetone reaction, these observations pave the way for development of general set of reaction mechanisms for the addition of CH to compounds containing an acetyl subgroup. The reaction of the methylidyne radical (CH) with acetone ((CH 3 ) 2 CQO) is studied at room temperature and at a pressure of 4 Torr (533.3 Pa) using a multiplexed photoionization mass spectrometer coupled to the tunable vacuum ultraviolet synchrotron radiation of the Advanced Light Source at Lawrence Berkeley National Laboratory. The CH radicals are generated by 248 nm multiphoton photolysis of bromoform and react with acetone in an excess of helium and nitrogen gas flow. The main observed reaction exit channel is elimination of a hydrogen atom to form C 4 H 6 O isomers. Analysis of photoionization spectra identifies dimethylketene and methacrolein as the only H-elimination products.The best fit to the data gives branching ratios of 0.68 AE 0.14 for methacrolein and 0.32 AE 0.07 for dimethylketene. A methylketene spectrum measured here is used to reanalyze the photoionization spectrum obtained at m/z = 56 for the CH + acetaldehyde reaction, (Goulay et al., J. Phys. Chem. A, 2012, 116, 6091) yielding new H-loss branching ratios of 0.61 AE 0.12 for acrolein and 0.39 AE 0.08 for methylketene. The contribution from methyleneoxirane to the reaction product distribution is revised to be negligible. Coupled with additional product detection for the CD + acetone reaction, these observations pave the way for development of general set of reaction mechanisms for the additi...

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“…One method of making these assignments is to compare the spectrum of fluoroethylene with those of chloro-, 31 bromo-, 32 and iodoethylene 33 obtained previously. Figure 12 shows the vertical I. P. 's of these molecules arranged as an orbital energy level diagram.…”

Section: H 3 Fmentioning

confidence: 99%

Variable angle photoelectron spectroscopy of the fluoroethylenes

Sell

Kuppermann

1979

The Journal of Chemical Physics

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He I photoelectron spectra of fluoroethylene, 1,1-difluoroethylene, cis-1,2-difluoroethylene, trans-1,2-difluoroethylene, trifluoroethylene, and perfluoroethylene were obtained over the scattering angle range of 45' to 120' and compared with those of ethylene. Vibrational frequencies of the ionic states were measured and their symmetry modes assigned. The asymmetry parameter /3 as a function of the ionization potential was measured for each molecule. The value of /3 for the first ionization potential band of these molecules was found to decrease monotonically with increasing fluorine substitution. This variation was interpreted as being due to resonance mixing of the lone pair F 1T orbitals with C-C 1T orbitals. The data obtained were used to assign some of the spectral bands observed.

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Photoelectron Spectra of Some Bromoethylenes and 2-Bromopropene

Cited by 41 publications

References 20 publications

Photoelectron spectroscopy of vinylbromide and intramolecular dynamics of the ionic B̃ state

Photoelectron spectroscopy of vinylbromide and intramolecular dynamics of the ionic B̃ state

Formation of dimethylketene and methacrolein by reaction of the CH radical with acetone

Variable angle photoelectron spectroscopy of the fluoroethylenes

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