Fluorescence from photoexcitation of C2H2 at 50–106 nm

Han, J. C.; Ye, Chao; Suto, Masako; Lee, L. C.

doi:10.1063/1.455810

Cited by 37 publications

(28 citation statements)

References 29 publications

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“…Furthermore, it is striking that for the similarly related species acetylene and cyanogen, the calculated partial channel (ion ground state) photoionization cross-section for C 2 H 2 69 is also 2-2.5 times greater than for C 2 N 2 70 up to 40 eV. Since the absorption cross-sections in the 15 eV region are roughly similar for acetylene [71][72][73] and cyanogen, 74 the difference in photoionization cross-sections in this energy region must be related to the ionization quantum yield which, according to the rule of thumb (which will only be a coarse-grained relation for these small species, neglecting shape resonances), will be greater by about a factor of 2.2 for acetylene with respect to cyanogen at 15 eV. Absorption studies of diacetylene and dicyanoacetylene in the 15 eV region are required in order to elucidate their relative photoionization cross-section behaviours.…”

Section: Discussionmentioning

confidence: 91%

Ionization photophysics and spectroscopy of dicyanoacetylene

Leach

Schwell

Garcı́a

et al. 2013

The Journal of Chemical Physics

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Photoionization of dicyanoacetylene was studied using synchrotron radiation over the excitation range 8-25 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and detailed spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of dicyanoacetylene was measured as 11.80 ± 0.01 eV. A detailed analysis of the cation spectroscopy involves new aspects and new assignments of the vibrational components to excitation of the quasi-degenerate A(2)Πg, B(2)Σg(+) states as well as the C(2)Σu(+) and D(2)Πu states of the cation. Some of the structured autoionization features observed in the 12.4-15 eV region of the total ion yield spectrum were assigned to vibrational components of valence shell transitions and to two previously unknown Rydberg series converging to the D(2)Πu state of C4N2(+). The appearance energies of the fragment ions C4N(+), C3N(+), C4(+), C2N(+), and C2(+) were measured and their heats of formation were determined and compared with existing literature values. Thermochemical calculations of the appearance potentials of these and other weaker ions were used to infer aspects of dissociative ionization pathways.

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Section: Discussionmentioning

confidence: 91%

Ionization photophysics and spectroscopy of dicyanoacetylene

Leach

Schwell

Garcı́a

et al. 2013

The Journal of Chemical Physics

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“…12 ,13 Extensive studies were also reported of C 2 H 2 excited above the first ionization potential. [4][5][6][13][14][15][16][17][18][19][20][21][22][23][24][25][26]5, cross sections were measured in detail. The compea) Present address: Department of Electronics, Kanazawa Institute of Techno!ogy, Nonoichi-machi, Ishikawa 921, Japan.…”

Section: Ionizing and Nonionizing Decays Of Superexcited Acetylene Momentioning

confidence: 99%

Ionizing and nonionizing decays of superexcited acetylene molecules in the extreme-ultraviolet region

Ukai

Kameta

Chiba

et al. 1991

The Journal of Chemical Physics

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Absolute measurements of the photoionization and photodissociation cross sections of C H h b d · .2 2 ave een rna e usmg contmuum monochromatized synchrotron radiation in the 53-93 nm region. The absolute photoabsorption cross section and photoionization quantum yield of C 2 H 2 have also been measured. The excitation spectra ofC, and H(Lyman-a) fluorescence have also been obtained. The obtained results have been compared with theoretical calculations. An unresolved problem of the spectral. interpretation concentrated on the (J * and 1T* shape resonances has been clarified by the ~tr~l~htforward demonstration of the photoionization quantum yield. The ionizing and nomomzmg decay processes of the superexcited C Z H 2 molecules have been discussed in view of the strong competition of autoionization and neutral dissociation. An overlapping nature of Rydberg states with the shape resonance is found to be important. 4142

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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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Fluorescence from photoexcitation of C2H2 at 50–106 nm

Cited by 37 publications

References 29 publications

Ionization photophysics and spectroscopy of dicyanoacetylene

Ionization photophysics and spectroscopy of dicyanoacetylene

Ionizing and nonionizing decays of superexcited acetylene molecules in the extreme-ultraviolet region

High-order harmonic generation from highly excited states in acetylene

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