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Photoexcitation and ionization in acetylene

Machado, L. E. and Leal, E. P. and Csanak, G. and McKoy, B. V. and Langhoff, P. W. (1982) Photoexcitation and ionization in acetylene. Journal of Electron Spectroscopy and Related Phenomena, 25 (1). pp. 1-27. ISSN 0368-2048. doi:10.1016/0368-2048(82)85001-9.

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Theoretical studies are reported of photoexcitation and ionization processes in the acetylene molecule. The calculations performed employ Franck—Condon and static-exchange approximations, and implicitly invoke vibrational and rotational closure. Detailed comparisons with recent spectral assignments, electron-impact excitation studies, and total and partial-channel cross-sectional measurements indicate that the theoretical results provide a useful first approximation to the complete dipole excitation/ionization spectrum of C_2H_2. The calculated discrete spectra are seen to include contributions from virtual 4σ_g(n/σ^*) and 1π_g(π^*) orbitals, which appear an valence interlopers in the 1π_u→ nsσ_g, 2σ_u → nsσ_g, 1σ_u → nsσ_g and 2σ_u → ndπ_g, 1σ_u → ndπ_g Rydberg series, respectively, in good accordance with spectral measurements. By contrast, the 3σ_u(σ^*) virtual valence orbital gives rise to prominent diabatic resonance features above threshold in the 3σ_g → kσ_u, 2σ_g → kσ_u, and 1σ_g → kσu cross-sections, results that are in good quantitative accordance with corresponding experimental studies. Prominent features in the measured (1π_u^(−1))X^2Π_u partial cross-section, which is in good accordance with the present values, are attributed to autoionization 2σ_u → 1π_g(π^*) and 4σ_g(n/σ^*) intravalence transitions.

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Additional Information:© 1982 Published by Elsevier B.V. Received 10 July 1981. It is a pleasure to acknowledge the support of the U S-Latin American Science Program, NSF(OIP)-CNPq (Brazil), of the Foundation for the Advancement of Science of the state of Sao Paulo (FAPESP), of the National Science Foundation, and the Donors of the Petroleum Research Fund, administered by the American Chemical Society. The kind hospitality of G H F Diercksen at the Max Planck Institut fur Astrophysik, Garching, to P W L is also gratefully acknowledged.
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U S-Latin American Science ProgramUNSPECIFIED
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)UNSPECIFIED
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)UNSPECIFIED
American Chemical Society Petroleum Research FundUNSPECIFIED
Max Planck Institut fur AstrophysikUNSPECIFIED
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Official Citation:L.E. Machado, E.P. Leal, G. Csanak, B.V. McKoy, P.W. Langhoff, Photoexcitation and ionization in acetylene, Journal of Electron Spectroscopy and Related Phenomena, Volume 25, Issue 1, 1982, Pages 1-27, ISSN 0368-2048, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:62182
Deposited By: Ruth Sustaita
Deposited On:18 Nov 2015 19:20
Last Modified:10 Nov 2021 22:59

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