Observation of the lowest 1Δ<i>u</i> Rydberg state of acetylene by multiphoton ionization spectroscopy

Fillion, J.-H.; Campos, A.; Pedersen, Jens Olaf Pepke; Shafizadeh, Niloufar; Gauyacq, D.

doi:10.1063/1.471866

Cited by 23 publications

(34 citation statements)

References 30 publications

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“…10. However, Fillion et al 69 have found that some of the vibrational assignments of Ref. 68 are not confirmed by their deuterium isotope shift measurements.…”

Section: Discussionmentioning

confidence: 95%

The bending vibrational levels of the acetylene cation: A case study of the Renner-Teller effect in a molecule with two degenerate bending vibrations

Tang

Chou

Lin

et al. 2006

The Journal of Chemical Physics

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Forty three vibronic levels of C2H2+, X 2Pi u, with upsilon4 = 0-6, upsilon5 = 0-3, and K = 0-4, lying at energies of 0-3520 cm(-1) above the zero-point level, have been recorded at rotational resolution. These levels were observed by double resonance, using 1+1' two-color pulsed-field ionization zero-kinetic-energy photoelectron spectroscopy. The intermediate states were single rovibrational levels chosen from the A1Au, 4nu3 (K = 1-2), 5nu3 (K = 1), nu2+4nu3 (K = 0), and 47,206 cm(-1) (K = 1) levels of C2H2. Seven of the trans-bending levels of C2H2+ (upsilon4 = 0-3, K = 0-2) had been reported previously by Pratt et al. [J. Chem. Phys. 99, 6233 (1993)]; our results for these levels agree well with theirs. A full analysis has been carried out, including the Renner-Teller effect and the vibrational anharmonicity for both the trans- and cis-bending vibrations. The rotational structure of the lowest 16 vibronic levels (consisting of the complete set of levels with upsilon4 + upsilon5 < or = 2, except for the unobserved upper (2Pi u component of the 2nu4 overtone) could be fitted by least squares using 16 parameters to give an rms deviation of 0.21 cm(-1). The vibronic coupling parameter epsilon5 (about whose magnitude there has been controversy) was determined to be -0.0273(7). For the higher vibronic levels, an additional parameter, r45, was needed to allow for the Darling-Dennison resonance between the two bending manifolds. Almost all the observed levels of the upsilon4 + upsilon5 = 3 and 4 polyads (about half of the predicted number) could then be assigned. In a final fit to 39 vibronic levels with upsilon4 + upsilon5 < or = 5, an rms deviation of 0.34 cm(-1) was obtained using 20 parameters. An interesting finding is that Hund's spin-coupling cases (a) and (b) both occur in the Sigmau components of the nu4 + 2nu5 combination level. The ionization potential of C2H2 (from the lowest rotational level of the ground state to the lowest rotational level of the cation) is found to be 91,953.77 +/- 0.09 cm(-1) (3sigma).

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“…10. However, Fillion et al 69 have found that some of the vibrational assignments of Ref. 68 are not confirmed by their deuterium isotope shift measurements.…”

Section: Discussionmentioning

confidence: 95%

The bending vibrational levels of the acetylene cation: A case study of the Renner-Teller effect in a molecule with two degenerate bending vibrations

Tang

Chou

Lin

et al. 2006

The Journal of Chemical Physics

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“…Since all origin bands of the Rydberg transitions are well characterized in the 3dϩ4s Rydberg complex, 32 the only possible Rydberg transitions should involve vibrational excitation of the upper state. The only Rydberg candidate in the 80 500-cm Ϫ1 region is the F 1 ⌺ u ϩ , 3d 1 0 2 band, by assuming a 1 frequency of about 2840 cm Ϫ1 for the F state.…”

Section: B the Mystery Of The Very Short Lifetime Of The H 1 ⌸ U Rydmentioning

confidence: 99%

Visible emission from the vibrationally hot C2H radical following vacuum-ultraviolet photolysis of acetylene: Experiment and theory

Boyé

Campos

Douin

et al. 2002

The Journal of Chemical Physics

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Photolysis of acetylene has been performed by vacuum-ultraviolet excitation with the synchrotron radiation via the Rydberg states converging to the first ionization potential ͑IP͒ at 11.4 eV. Only the visible fluorescence of the ethynyl radical was observed in the Ã 2 ⌸-X 2 ⌺ ϩ system. Excitation of several Rydberg states of acetylene over a large energy range between 9 and 11.4 eV allowed us to observe for the first time the evolution of this continuum with increasing Rydberg excitation. Intensity calculations based on accurate ab initio potential energy surfaces of C 2 H were performed by using a one-dimensional model accounting for the large-amplitude motion of the H atom around the CC bond and for the overall rotation of the radical. These calculations successfully reproduce the observed visible continuum ͑maximum at 500 nm and blue side cutoff at 400 nm͒ and bring new information on the distribution of the internal energy deposited in the fragment. For most excited Rydberg states, predissociation occurs in a rather low time scale, leaving the C 2 H fragment in the Ã state, vibrationally hot, mostly with significant excitation in the bending mode around the isomerization barrier.

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“…In particular, many UV absorption bands involving the nsσ g , 1 Π u and ndδ g , 1 Π u series for the four isotopomers C 2 H 2 , C 2 D 2 , 13 C 2 H 2 and C 2 HD have been rotationally analysed, while other absorption bands involving the ndσ g , 1 Π u and ndπ g , 1 Σ + u series appear completely diffuse for all n values (Colin et al 1977;Herman & Colin 1982). More recent REMPI studies involving one-colour threephoton excitation have been carried out on the ungerade Rydberg states (Ashfold et al 1985(Ashfold et al , 1986Orlando et al 1986Orlando et al , 1987Fillion et al 1996), and allowed for the observation of new electronic components of the ns and nd series, namely the ndδ g , 1 Φ u state (Ashfold et al 1985) and the ndπ g , 1 ∆ u state (Fillion et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Spectroscopy and dynamics of the Rydberg states of C ₂ H ₂ and their relevance to astrophysical photochemistry

Shafizadeh

Fillion

Gauyacq

et al. 1997

Philosophical Transactions of the Royal Society of London. Seri

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In order to understand the role of the Rydberg states in the photodestruction of acetylene in circumstellar envelopes, we have investigated the spectroscopy of some of the ungerade and gerade states by resonant multiphoton ionization in a magnetic bottle photoelectron spectrometer. The ungerade ns + nd Rydberg supercomplexes of C 2 H 2 have been investigated by one-colour (3 + 1) multiphoton ionization, in the energy region 79 500-87 000 cm −1 . Our spectral data show a very different behaviour of the various components of these supercomplexes towards predissociation. The highly excited gerade nf Rydberg states have been observed for the first time, by twocolour (3 + 1 ) multiphoton ionization. A value for the adiabatic ionization potential, 91 956 cm −1 , has been obtained from the observed series limit and from earlier highresolution infrared data on the ground state of the ion. This value is 4 cm −1 higher than the one measured by ZEKE spectroscopy. The apparent broadening of the observed Rydberg features may originate both from Zeeman 'broadening' of the non-penetrating nf complexes and from predissociation. The np Rydberg states, for which observation is fully allowed in the same spectral region, do not appear in the ionization signal at least in the low-n range, most probably because of their very short lifetime. In the high-energy region, spectral congestion, probably involving p-f mixing, occurs.

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Observation of the lowest 1Δu Rydberg state of acetylene by multiphoton ionization spectroscopy

Cited by 23 publications

References 30 publications

The bending vibrational levels of the acetylene cation: A case study of the Renner-Teller effect in a molecule with two degenerate bending vibrations

The bending vibrational levels of the acetylene cation: A case study of the Renner-Teller effect in a molecule with two degenerate bending vibrations

Visible emission from the vibrationally hot C2H radical following vacuum-ultraviolet photolysis of acetylene: Experiment and theory

Spectroscopy and dynamics of the Rydberg states of C ₂ H ₂ and their relevance to astrophysical photochemistry

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Observation of the lowest 1Δu Rydberg state of acetylene by multiphoton ionization spectroscopy

Cited by 23 publications

References 30 publications

The bending vibrational levels of the acetylene cation: A case study of the Renner-Teller effect in a molecule with two degenerate bending vibrations

The bending vibrational levels of the acetylene cation: A case study of the Renner-Teller effect in a molecule with two degenerate bending vibrations

Visible emission from the vibrationally hot C2H radical following vacuum-ultraviolet photolysis of acetylene: Experiment and theory

Spectroscopy and dynamics of the Rydberg states of C 2 H 2 and their relevance to astrophysical photochemistry

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Spectroscopy and dynamics of the Rydberg states of C ₂ H ₂ and their relevance to astrophysical photochemistry