Excited states of the polyacetylenes. Analysis of the near ultraviolet spectra of diacetylene and triacetylene

Haink, H. J.; Jungen, Martin

doi:10.1016/0009-2614(79)80652-1

Cited by 40 publications

(37 citation statements)

References 11 publications

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“…None of the resonances observed in the present VE study explains the more intense (73 pm 2 ) DEA band at 5.25 eV, both in terms of energy and in terms of autodetachment width, and we conclude that this DEA band must be due to core-excited resonance(s), with one of the (π,π * ) valence excited states ∼5 eV [44,45] as the parent state. We point out, however, that at least some resonances in the 5-eV range are likely to be affected by configuration mixing, since the 2 (π g ) shape and the 2 (π g ,π 2 u ) core-excited configurations have the same symmetry (and multiplicity) and can mix.…”

Section: Discussioncontrasting

confidence: 69%

“…It is interesting to note that entirely different angular distributions were observed in the closely related case of acetylene [44,45] (the extra electron could be captured in a diffuse 3s-like σ g orbital in the resonance), but that it is at 4.8 eV, too high for a vertical electron capture at 1 eV. A 1-eV electron must be, at least initially, captured into the 2 u shape resonance.…”

Section: Cross Sections For Vibrational Excitationmentioning

confidence: 94%

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Absolute angle-differential vibrational excitation cross sections for electron collisions with diacetylene

et al. 2011

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Absolute vibrational excitation cross sections were measured for diacetylene (1,3-butadiyne). The selectivity of vibrational excitation reveals detailed information about the shape resonances. Excitation of the C≡C stretch and of double quanta of the C−H bend vibrations reveals a 2 u resonance at 1 eV (autodetachment width ∼30 meV) and a 2 g resonance at 6.2 eV (autodetachment width 1-2 eV). There is a strong preference for excitation of even quanta of the bending vibration. Excitation of the C−H stretch vibration reveals σ * resonances at 4.3, 6.8, and 9.8 eV, with autodetachment widths of ∼2 eV. Detailed information about resonances permits conclusions about the mechanism of the dissociative electron attachment.

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Section: Discussioncontrasting

confidence: 69%

Section: Cross Sections For Vibrational Excitationmentioning

confidence: 94%

Absolute angle-differential vibrational excitation cross sections for electron collisions with diacetylene

et al. 2011

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“…8 Spectroscopic studies of C 4 H 2 are abundant in the UV and VUV region. [9][10][11] The spectrum between 195 and 225 nm shows structured vibrational progressions, which is assigned to a 1 u ← 1 g + forbidden electronic transition. 9 No freeradical products were detected for C 4 H 2 photolysis in this region.…”

Section: Introductionmentioning

confidence: 99%

“…[9][10][11] The spectrum between 195 and 225 nm shows structured vibrational progressions, which is assigned to a 1 u ← 1 g + forbidden electronic transition. 9 No freeradical products were detected for C 4 H 2 photolysis in this region. 12 The dissociation quantum yield was ascribed to reactivity of a long-lived metastable form, usually assumed to the lowest triplet state.…”

Section: Introductionmentioning

confidence: 99%

Photodissociation dynamics of C4H2 at 164.41 nm: Competitive dissociation pathways

Zhang

et al. 2013

The Journal of Chemical Physics

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Photodissociation dynamics of C 4 H 2 at 164.41 nm through the Rydberg state R( 1 u ) have been studied using the high-resolution H atom Rydberg tagging technique. Experimental evidences show that two different predissociation pathways exist to form the ground C 4 H (X 2 + ) and electronically excited C 4 H (A 2 ) products: the former has statistical and isotropic translational energy distribution through internal conversion (IC) to the ground state, while the latter has non-statistical and anisotropic translational energy distribution through IC to the excited repulsive state. The vibrational progressions of C 4 H (A 2 ) products have also been observed and assigned.

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“…It is noteworthy that compounds like diacetylene, which has a relatively high concentration in the same region of the flame, present an u.v. absorption cross section which is much lower than those of PAH [81]. An unambiguous attribution of the fluorescence spectra is not possible at the moment.…”

mentioning

confidence: 80%

Laser Light Scattering and Fluorescence Diagnostics of Rich Flames Produced by Gaseous and Liquid Fuels

D’Alessio

1981

Particulate Carbon

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Rich combustion systems present a much more complex chemistry than stoichiometric or lean ones: compounds from unsaturated C2 hydrocarbons to polynuclear aromatic hydrocarbons (P AH) are formed and destroyed, soot particles nucleate, grow and agglomerate and eventually burn out at different stages of the combustion. Furthermore, the fuel is introduced in the form of liquid droplets in many practical systems.The present paper presents initially a short summary of the scattering and extinction properties of spherical particles, from the Rayleigh regime to the ray optics limit (geometric regime), referring particularly to the simultaneous presence of soot particles and fuel droplets.Problems connected with polydispersion of spheres and the presence of particles of different shapes (spheroids, clusters, chains, etc.) are also briefly discussed.The paper reviews subsequently the u. v ./visible absorption and fluorescence spectra of some P AH compounds and discusses their interferences with the extinction due to soot particles and/or droplets and the spontaneous Raman effects due to low molecular mass compounds. The experimental section presents initially some laser light scattering (LLS) and extinction measurements carried out on large diesel oil spray flames. A procedure for distinguishing between fuel droplets and soot particles is illustrated, and average size and number concentration of soot particlesare evaluated. The effects of swirl on the spatial distribution of soot particles and fuel droplets for these types of flames are also shown. Optical results obtained on premixed and diffusion CH402 flames are compared in the next section: LLS measurements provide evidence for zones of early formation of soot particles while u. v. absorption and fluorescence spectra are related to the build-up ofPAH compounds.The final part of the paper compares the experimental results with the theoretical models and discusses agreement and limits; suggestions are LIST OF SYMBOLS

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Excited states of the polyacetylenes. Analysis of the near ultraviolet spectra of diacetylene and triacetylene

Cited by 40 publications

References 11 publications

Absolute angle-differential vibrational excitation cross sections for electron collisions with diacetylene

Absolute angle-differential vibrational excitation cross sections for electron collisions with diacetylene

Photodissociation dynamics of C4H2 at 164.41 nm: Competitive dissociation pathways

Laser Light Scattering and Fluorescence Diagnostics of Rich Flames Produced by Gaseous and Liquid Fuels

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