کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5376279 | 1504318 | 2007 | 13 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The electronic states of but-2-yne studied by VUV absorption, near-threshold electron energy-loss spectroscopy and ab initio configuration interaction methods
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The lowest valence singlet states are ÏÏâ, optically forbidden, and calculated to lie near 7.3 and 7.6 eV. The states which contribute strongly to the observed spectrum are ÏÏâ(1Eâ²+1A2â³) near 7.9 eV having 2eâ²6a1â²â excitation, followed by several ÏÏâ and ÏÏâ states (1Eâ²+1A2â³) between 10.0 and 10.5 eV; an 1Eâ² antisymmetric combination(2eâ²2eâ³Â â 2eâ²2eâ³) is by far the strongest in intensity. A further group of symmetry-allowed valence states are calculated to lie near 12.3 and 12.9 eV. The two lowest triplet states, both of Eâ² symmetry (ÏÏâ), have vertical excitation energies of 5.7 and 6.2 eV, but are strongly bent with a trans-CCCC unit (CS and C2h). The theoretical work confirms that, on intensity grounds, valence excited states do not contribute significantly to the spectrum. CI calculations of the ionic states give the ionisation energy sequence (D3h): 2Eâ²<2A1â²<2Eâ³<2Eâ²<2A2â³. Adiabatic structures for the first cation, two triplets, and a singlet (C2h) were obtained; these show shortening of C-C, and lengthening of CC, in a trans-CCCC, as is found with ethyne.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Physics - Volume 340, Issues 1â3, 9 November 2007, Pages 158-170
Journal: Chemical Physics - Volume 340, Issues 1â3, 9 November 2007, Pages 158-170
نویسندگان
Michael H. Palmer, Isobel C. Walker,