Autoionizing resonance in photoionization from the 1π<i>u</i> level of acetylene

Mitsuke, Koichiro; Hattori, Hideo

doi:10.1063/1.469254

Cited by 17 publications

(8 citation statements)

References 16 publications

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“…38 Although various opinions have attempted to account for the nature of the 13.3 eV underlying resonance, Mitsuke and Hattori unambiguously identified the 13.3 eV feature as autoionization from the 3 g Ϫ1 3 u 1 state based on photoelectron and constant-ion-state ͑CIS͒ spectra. 39 Also by employing the CIS spectroscopy, autoionization of the * shape resonance correlated to the 1 u Ϫ1 state was observed at around 15.5 eV ͑80 nm͒. 40 In a quantitatively aspect, a detailed photoabsorption and photoionization studies by Ukai et al identified *, *, and * shape resonances at 13.3, 15.5, and 17.7 eV, respectively.…”

Section: Absolute Branching Ratios Photoionization Quantum Yield Anmentioning

confidence: 98%

Photoabsorption and photoionization of propyne

Lin

Wang

et al. 1998

The Journal of Chemical Physics

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This work measured the absolute photoabsorption cross section of propyne (methylacetylene, CH3CCH) in the 6–30 eV energy range. The valence-shell oscillator strength of 16.97 and the static dipole polarizability of 35.82 atomic units (5.31 Å3) were also derived from the photoabsorption spectrum by the sum-rule method. In the photoionization measurement, the first ionization energy 10.369±0.007 eV of propyne and appearance energies for ion fragments were determined. In addition, new vibrational ν9 and ν10 progressions associated with the X 2E ion state of propyne and Rydberg transitions converged to the A 2E ion state were identified. In addition to the main ν3 progression with the vibrational interval of 1979±39 cm−1, the ν9 and ν10 vibrational structures of the X 2E ion state were resolved with vibrational frequencies of 586±74 cm−1 and 289±65 cm−1, respectively. Moreover, the absolute branching ratios, photoionization quantum yield, and partial photoionization cross sections for C3H4+, C3H3+, C3H2+, and C3H+ production in the 10.3–21.4 eV region were determined. Four shape resonance states were tentatively assigned at 11.2, 12.7, 14.8 and 15.8, and 16.7 eV. Furthermore, a CD3CCH isotopic measurement was taken to examine the reaction pathways of H-dissociative photoionization of propyne. According to the evolution of the C3D3+/C3D2H+ ratio, plausible decay mechanisms for H-dissociative photoionization of propyne were proposed.

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Section: Absolute Branching Ratios Photoionization Quantum Yield Anmentioning

confidence: 98%

Photoabsorption and photoionization of propyne

Lin

Wang

et al. 1998

The Journal of Chemical Physics

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“…[ [23][24][25][26][27][28]. In particular, features in the photoionization spectrum around 0.4963 hartree in the photon energy are generally associated with the formation and subsequent autoionization of the 3σ g → 3σ u excited state [26,27].…”

Section: B High-order Harmonic Generation: the Ir Pulsementioning

confidence: 99%

“…It is widely known that resonance phenomena greatly influence photoabsorption and photoionization cross sections in acetylene [20][21][22][23][24][25][26][27][28]. While many studies have considered excitations from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), there is much interest in the role of highly excited states in photoabsorption and photoionization at vacuum ultraviolet (VUV) wavelengths [23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

“…While many studies have considered excitations from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), there is much interest in the role of highly excited states in photoabsorption and photoionization at vacuum ultraviolet (VUV) wavelengths [23][24][25][26][27][28]. Therefore, we can envisage that these highly excited states can give rise to several possible mechanisms for HHG.…”

Section: Introductionmentioning

confidence: 99%

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High-order harmonic generation from highly excited states in acetylene

Mulholland

Dundas

2018

Phys. Rev. A

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High-order harmonic generation (HHG) from aligned acetylene molecules interacting with mid infra-red (IR), linearly polarized laser pulses is studied theoretically using a mixed quantum-classical approach in which the electrons are described using time-dependent density functional theory while the ions are treated classically. We find that for molecules aligned perpendicular to the laser polarization axis, HHG arises from the highestoccupied molecular orbital (HOMO) while for molecules aligned along the laser polarization axis, HHG is dominated by the HOMO-1. In the parallel orientation we observe a double plateau with an inner plateau that is produced by ionization from and recombination back to an autoionizing state. Two pieces of evidence support this idea. Firstly, by choosing a suitably tuned vacuum ultraviolet pump pulse that directly excites the autoionizing state we observe a dramatic enhancement of all harmonics in the inner plateau. Secondly, in certain circumstances, the position of the inner plateau cut-off does not agree with the classical three-step model. We show that this discrepancy can be understood in terms of a minimum in the dipole recombination matrix element from the continuum to the autoionizing state. As far as we are aware, this represents the first observation of harmonic enhancement over a wide range of frequencies arising from autoionizing states in molecules.

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“…1 One example of this occurs with photoionization into the X 2 ⌸ u state of acetylene; experimental results for this system in the ϳ11.4-16.6 eV photon energy region reveal a complicated structure, about which there has existed a long-standing controversy concerning the exact assignment of experimentally observed structures and the attendant dynamics of photoionization giving rise to same. [2][3][4][5][6][7][8][9][10][11][12][13][14][15] Concurrent with this experimentally driven controversy, there has been a significant amount of theoretical work. 2,11,12,[16][17][18][19] The theoretical work to date has contributed much to clarify the situation, but so far has not resolved all issues.…”

Section: Introductionmentioning

confidence: 99%

The outer valence photoionization of acetylene

Wells

Lucchese

1999

The Journal of Chemical Physics

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We report fixed-nuclei photoionization cross-sections and asymmetry parameters for photoionization leading to the X 2Πu, A 2Σg+, B 2Σu+, and C 2Σg+ states of acetylene with emphasis on the first four states. The magnitude of the photoionization cross-sections calculated here is in excellent agreement with recent experiment at both low and high photon energy. Further, as a result of the multichannel scattering methodology used to perform the calculation, the partial channel cross-sections and asymmetry parameters reported here resolve significant structure arising from indirect photoionization processes such as autoionization. Although vibrational degrees of freedom are not included within the fixed nuclei framework employed here, we find that, even without vibrational degrees of freedom, the present theoretical results generally exhibit the same detailed features as the experimental results, both for conventional photoionization spectra and, as a result of vibrational autoionization, for threshold photoionization spectra. This general agreement suggests that a large part of the structure in the low energy or outer valence photoionization spectrum of acetylene is explicable solely in terms of Rydberg transitions. This study also predicts that dark states may cause some appreciable distortion of the profile of the photoionization asymmetry parameter in the photon region of ∼20–21.5 eV as a result of final state correlations with more intense states.

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Autoionizing resonance in photoionization from the 1πu level of acetylene

Cited by 17 publications

References 16 publications

Photoabsorption and photoionization of propyne

Photoabsorption and photoionization of propyne

High-order harmonic generation from highly excited states in acetylene

The outer valence photoionization of acetylene

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