Experimental and theoretical investigation of the photoionization of acetylene

Kreile, Jürgen; Schweig, Armin; Thiel, Walter

doi:10.1016/0009-2614(81)85033-6

Cited by 35 publications

(11 citation statements)

References 28 publications

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“…When experiments are conducted at a constant incident light intensity the ionization rate for different Rydberg states will depend on their respective ionization crosssections--about which very little information is currently available. It may be pertinent to note, however, that measurements of the acetylene ground state photoionization cross-section [36][37][38][39][40] and of the asymmetry parameter characterising the resulting photoelectron angular distributions [38][39][40] all indicate the existence of a broad resonance centred about 2-6 eV above the first ionization potential. The origin of this resonance, which spans the energy region accessed by the fourth photon in the present experiments, remains the subject of some controversy [41].…”

Section: Ashfold Et Almentioning

confidence: 99%

A¹Φ_uRydberg state of acetylene revealed by gas phase multiphoton ionization spectroscopy

et al. 1985

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A new Rydberg state of acetylene has been identified as a three photon resonance in the four photon ionization spectra of both C2H 2 and C2D 2 . In both isotopic species the zero point level of this new electronic state is sufficiently long lived to support rotational structure. Spectral analysis, including use of the appropriate three photon rotational linestrength theory, enables characterization of the excited state symmetry as 10 u. Quantum defect considerations, and comparisons with recent ab initio calculations, encourage assignment of this 10 u state in terms of the electronic promotion n 3 3d69 ~-n u .~ Possible reasons for the dominance of this 10u-aY+g transition in the 3 + 1 MPI spectrum of acetylene are considered.

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Section: Ashfold Et Almentioning

confidence: 99%

A¹Φ_uRydberg state of acetylene revealed by gas phase multiphoton ionization spectroscopy

et al. 1985

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“…This phenomenon was first observed on ethene,11 but the photoionization of acetylene has been a topic of intense experimental and theoretical studies. Since the 1960s, many works have treated this subject 12–25. Special interest has been paid to the inner valence satellite spectrum of acetylene.…”

Section: Introductionmentioning

confidence: 99%

Vertical spectrum of the C₂H system. An open shell (SC)²‐CAS‐SDCI study

2003

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The open shell (SC)(2)-CAS-SDCI method along with a basis set of atomic natural orbitals (ANO) has been applied for calculating the main ionization potentials of acetylene, as well as the manifold of excited states of the different symmetries up to 32 eV. In this method, the single and double excitations of a CAS space are generated and the corresponding CI matrix is corrected by means of the (SC)(2) procedure that cancels the size-extensivity error and adds some high order contributions. The mean absolute error for the outer-valence X (2)Pi(u)(1pi(u) (-1)), A (2)Sigma(g) (+)(3sigma(g) (-1)), and B (2)Sigma(u) (+)(2sigma(u) (-1)) states, and the inner-valence C (2)Sigma(g) (+)(2sigma(g) (-1)) state is 0.1 eV. The excited states of C(2)H(2) (+) corresponding to the Sigma(g) (+), Sigma(u) (+), Pi(g), Pi(u), Delta(g), and Delta(u) symmetries are reported and their composition is discussed. The results are thoroughly compared to the best available multireference CI calculations. Recent multichannel CI results by Wells and Lucchese [J Chem Phys 1999, 110, 6365] have been used also as a guide for the discussion of the results. Discrepancies in the description of many multiconfigurational states by means of the (SC)(2)-CAS-SDCI wave function as compared to previous large MR-CI calculations are significant and are, consequently, remarked on. A large mixing of the 3sigma(g) (-1) and 2sigma(g) (-1) processes is found in the A (2)Sigma(g) (+) and C (2)Sigma(g) (+) states, provided that the basis set is augmented with Rydberg functions.

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“…Several groups measured photoelectron spectra for the C 2 H 2 ϩ (X 2 ⌸ u ) band using synchrotron radiation 6,7,9,10 and discrete line sources. 8 At photon energies below 16 eV, they reported non-Franck-Condon behavior in the vibrational distribution among the v 2 ϭ0-2 levels of the C-C stretching mode 2 , 6-10 and excitation of bending vibration in addition. 10 Theoretically, the cross section curve cannot be reproduced by an independent-particle approximation as long as resonance effect is not taken into account.…”

Section: Introductionmentioning

confidence: 99%

“…Another reason why C 2 H 2 has attracted considerable attention is that the cross section for photoionization of the 1 u level shows a conspicuous double-bump structure at photon energies of 13-16 eV. [3][4][5][6][7][8][9][10][11][12] Peak maxima are located at ϳ13.3 and ϳ15.3 eV. This rather stimulative structure has promoted close cooperation between experiment and theory in order to gain insight into the dynamics of resonant photoionization of C 2 H 2 .…”

Section: Introductionmentioning

confidence: 99%

Autoionizing resonance in photoionization from the 1πu level of acetylene

Mitsuke

Hattori

1995

The Journal of Chemical Physics

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Autoionizing resonance of acetylene is studied by photoelectron spectroscopy using synchrotron radiation. Pronounced vibrational excitation in the C-H stretching mode 1 is observed in the (1 u ) Ϫ1 X 2 ⌸ u band of C 2 H 2 ϩ at a restricted photon energy range from 12.8 to 14.1 eV. It is concluded that the 3 g →3 u autoionizing transition at ϳ13.3 eV gives rise to an anomalously broad maximum in the ͑1 u ͒ Ϫ1 photoionization cross section curve. The strong 1 excitation is explained as that the equilibrium C-H bond length differs from the neutral and ionic ground states to the (3 g ) Ϫ1 (3 u ) 1 resonance state. Constant ionic state spectra for the v 1 ϭ3 and 4 levels of the X 2 ⌸ u state measured over the same energy region show fine structures with regular spacings corresponding to the vibrational levels of the (3 g ) Ϫ1 (3 u ) 1 state.

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Experimental and theoretical investigation of the photoionization of acetylene

Cited by 35 publications

References 28 publications

A¹Φ_uRydberg state of acetylene revealed by gas phase multiphoton ionization spectroscopy

A¹Φ_uRydberg state of acetylene revealed by gas phase multiphoton ionization spectroscopy

Vertical spectrum of the C₂H system. An open shell (SC)²‐CAS‐SDCI study

Autoionizing resonance in photoionization from the 1πu level of acetylene

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Experimental and theoretical investigation of the photoionization of acetylene

Cited by 35 publications

References 28 publications

A1ΦuRydberg state of acetylene revealed by gas phase multiphoton ionization spectroscopy

A1ΦuRydberg state of acetylene revealed by gas phase multiphoton ionization spectroscopy

Vertical spectrum of the C2H system. An open shell (SC)2‐CAS‐SDCI study

Autoionizing resonance in photoionization from the 1πu level of acetylene

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A¹Φ_uRydberg state of acetylene revealed by gas phase multiphoton ionization spectroscopy

A¹Φ_uRydberg state of acetylene revealed by gas phase multiphoton ionization spectroscopy

Vertical spectrum of the C₂H system. An open shell (SC)²‐CAS‐SDCI study