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Wang YJ, Hsu YC. Vibrational predissociation in the bending levels of the à state of C 3Ar. J Chem Phys 2020; 153:124303. [PMID: 33003725 DOI: 10.1063/5.0015592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Vibrational predissociation (VP) has been observed in 16 bands of the C3Ar van der Waals complex near the 0 v2 0 - 000 (v2 = 2-, 4-, 2+) and 0 2- 2 - 100 bands of the Ã1Π-X̃1Σ+ g system of C3. New higher resolution wavelength-resolved emission (WRE) spectra covering a wider spectral range have been recorded for many of these C3Ar bands, which show that most of the features observed in fluorescence must be reassigned as emission from the C3 fragment. Two types of VP processes have been recognized. The first type gives rise to vibrationally hot C3 fragments, mostly following |Δv| = 1, |ΔP| = 1 propensity rules, where P is the vibronic angular momentum of C3. The second type gives vibrationally cooled fragments. The VP processes can change abruptly from one type to the other with comparatively small differences in vibrational energy. Although the initial states are associated with both orbital components of the C3, Ã1Πu state, most of the VP fragments belong to the lower orbital component. A dipole-induced dipole model has been used to interpret the observed ΔP- propensities. Ab initio calculations of the binding energies of the ground and excited electronic states of C3Ar have been carried out; the calculated values are consistent with estimates of ≤144 cm-1 and 164 cm-1, respectively, given by the WRE spectra.
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Affiliation(s)
- Yi-Jen Wang
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei, Taiwan and Department of Physics, National Central University, 300 Jhongda Rd., Jhongli, 32001, Taoyuan, Taiwan
| | - Yen-Chu Hsu
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei, Taiwan and Department of Physics, National Central University, 300 Jhongda Rd., Jhongli, 32001, Taoyuan, Taiwan
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Schröder B, Doney KD, Sebald P, Zhao D, Linnartz H. Stretching our understanding of C 3: Experimental and theoretical spectroscopy of highly excited nν 1 + mν 3 states (n ≤ 7 and m ≤ 3). J Chem Phys 2018; 149:014302. [PMID: 29981549 DOI: 10.1063/1.5034092] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We present the high resolution infrared detection of fifteen highly vibrationally excited nν1 + mν3 combination bands (n ≤ 7 and m ≤ 3) of C3 produced in a supersonically expanding propyne plasma, of which fourteen are reported for the first time. The fully resolved spectrum, around 3 μm, is recorded using continuous wave cavity ring-down spectroscopy. A detailed analysis of the resulting spectra is provided by ro-vibrational calculations based on an accurate local ab initio potential energy surface for C3 (X̃1Σg+). The experimental results not only offer a significant extension of the available data set, extending the observed number of quanta v1 to 7 and v3 to 3, but also a vital test to the fundamental understanding of this benchmark molecule. The present variational calculations give remarkable agreement compared to experimental values with typical accuracies of ∼0.01% for the vibrational frequencies and ∼0.001% for the rotational parameters, even for high energy levels around 10 000 cm-1.
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Affiliation(s)
- Benjamin Schröder
- Universität Göttingen, Institut für Physikalische Chemie, Göttingen D-37077, Germany
| | - Kirstin D Doney
- Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
| | - Peter Sebald
- Universität Göttingen, Institut für Physikalische Chemie, Göttingen D-37077, Germany
| | - Dongfeng Zhao
- CAS Center for Excellence in Quantum Information and Quantum Physics and Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Harold Linnartz
- Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
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Rocha CMR, Varandas AJC. Multiple conical intersections in small linear parameter Jahn-Teller systems: the DMBE potential energy surface of ground-state C 3 revisited. Phys Chem Chem Phys 2018; 20:10319-10331. [PMID: 29610812 DOI: 10.1039/c7cp06656b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new single-sheeted DMBE potential energy surface for ground-state C3 is reported. The novel analytical form accurately describes the three symmetry-equivalent C2v disjoint seams, in addition to the symmetry-required D3h one, over the entire configuration space. The present formalism warrants by built-in construction the confluence of the above crossings, and the rotation-in-plane of the C2v seams when the perimeter of the molecule fluctuates. Up to 1050 ab initio energies have been employed in the calibration procedure, of which 421 map the loci of intersection. The calculated energies have been scaled to account for the incompleteness of the basis set and truncation of the MRCI expansion, and fitted analytically with chemical accuracy. The novel form is shown to accurately mimic the region defined by the 4 conical intersections, while exhibiting similar attributes to the previously reported one [J. Chem. Phys., 2015, 143, 074302] at the regions of configuration space away from the crossing seams. Despite being mainly addressed to C3, the present approach should be applicable to adiabatic PESs of any X3 system experiencing similar topological attributes, in particular the small-linear-parameter Jahn-Teller molecules.
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Affiliation(s)
- C M R Rocha
- Departamento de Química, and Centro de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal.
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Varandas AJC, Rocha CMR. Cn ( n=2-4): current status. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2017.0145. [PMID: 29431687 PMCID: PMC5805914 DOI: 10.1098/rsta.2017.0145] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/27/2017] [Indexed: 05/28/2023]
Abstract
The major aspects of the C2, C3 and C4 elemental carbon clusters are surveyed. For C2, a brief analysis of its current status is presented. Regarding C3, the most recent results obtained in our group are reviewed with emphasis on modelling its potential energy surface which is particularly complicated due to the presence of multiple conical intersections. As for C4, the most stable isomeric forms of both triplet and singlet spin states and their possible interconversion pathways are examined afresh by means of accurate ab initio calculations. The main strategies for modelling the ground triplet C4 potential are also discussed. Starting from a truncated cluster expansion and a previously reported DMBE form for C3, an approximate four-body term is calibrated from the ab initio energies. The final six-dimensional global DMBE form so obtained reproduces all known topographical aspects while providing an accurate description of the C4 linear-rhombic isomerization pathway. It is therefore commended for both spectroscopic and reaction dynamics studies.This article is part of the theme issue 'Modern theoretical chemistry'.
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Affiliation(s)
- A J C Varandas
- Department of Chemistry and Coimbra Chemistry Center, University of Coimbra 3004-535 Coimbra, Portugal
| | - C M R Rocha
- Department of Chemistry and Coimbra Chemistry Center, University of Coimbra 3004-535 Coimbra, Portugal
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Breier AA, Büchling T, Schnierer R, Lutter V, Fuchs GW, Yamada KMT, Mookerjea B, Stutzki J, Giesen TF. Lowest bending mode of 13C-substituted C 3 and an experimentally derived structure. J Chem Phys 2017; 145:234302. [PMID: 28010092 DOI: 10.1063/1.4971854] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The ν2 lowest bending mode of linear C3 and of all its 13C-substituted isotopologues was recorded using a terahertz-supersonic jet spectrometer in combination with a laser ablation source. Sixty-five ro-vibrational transitions between 1.8 and 1.9 THz have been assigned to linear C12C12C12, C12C12C13, C12C13C12, C13C13C12, C13C12C13, and C13C13C13. For each isotopologue, molecular parameters were obtained and the C-C-bond length was derived experimentally. All results are in excellent agreement with recent ab initio calculations [B. Schröder and P. Sebald, J. Chem. Phys. 144, 044307 (2016)]. The new measurements explain why the interstellar search for singly substituted C12C12C13 has failed so far. A spectral line list with recommended transition frequencies based on global data fits is given to foster future interstellar detections.
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Affiliation(s)
- Alexander A Breier
- Laboratory Astrophysics, Institute of Physics, University of Kassel, 34132 Kassel, Germany
| | - Thomas Büchling
- Laboratory Astrophysics, Institute of Physics, University of Kassel, 34132 Kassel, Germany
| | - Rico Schnierer
- Physics of New Materials, Institute of Physics, University of Rostock, 18059 Rostock, Germany
| | - Volker Lutter
- Laboratory Astrophysics, Institute of Physics, University of Kassel, 34132 Kassel, Germany
| | - Guido W Fuchs
- Laboratory Astrophysics, Institute of Physics, University of Kassel, 34132 Kassel, Germany
| | | | - Bhaswati Mookerjea
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Jürgen Stutzki
- I. Physikalisches Institute, Universität zu Köln, 50937 Köln, Germany
| | - Thomas F Giesen
- Laboratory Astrophysics, Institute of Physics, University of Kassel, 34132 Kassel, Germany
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Schröder B, Sebald P. High-level theoretical rovibrational spectroscopy beyond fc-CCSD(T): The C3 molecule. J Chem Phys 2016; 144:044307. [PMID: 26827217 DOI: 10.1063/1.4940780] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
An accurate local (near-equilibrium) potential energy surface (PES) is reported for the C3 molecule in its electronic ground state (X̃(1)Σg (+)). Special care has been taken in the convergence of the potential relative to high-order correlation effects, core-valence correlation, basis set size, and scalar relativity. Based on the aforementioned PES, several rovibrational states of all (12)C and (13)C substituted isotopologues have been investigated, and spectroscopic parameters based on term energies up to J = 30 have been calculated. Available experimental vibrational term energies are reproduced to better than 1 cm(-1) and rotational constants show relative errors of not more than 0.01%. The equilibrium bond length has been determined in a mixed experimental/theoretical approach to be 1.294 07(10) Å in excellent agreement with the ab initio composite value of 1.293 97 Å. Theoretical band intensities based on a newly developed electric dipole moment function also suggest that the infrared active (1, 1(1), 0)←(0, 0(0), 0) combination band might be observable by high-resolution spectroscopy.
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Affiliation(s)
- Benjamin Schröder
- Institut für Physikalische Chemie, Georg August Universität Göttingen, Göttingen D-37077, Germany
| | - Peter Sebald
- Institut für Physikalische Chemie, Georg August Universität Göttingen, Göttingen D-37077, Germany
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Merer AJ, Hsu YC, Chen YR, Wang YJ. Rotational analysis of bands of the à - X̃ transition of the C3Ar van der Waals complex. J Chem Phys 2015; 143:194304. [PMID: 26590534 DOI: 10.1063/1.4935368] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Rotational analyses have been carried out for four of the strongest bands of the Ã-X̃ transition of the C3Ar van der Waals complex, at 393 and 399 nm. These bands lie near the 02(-)0-000 and 04(-)0-000 bands of the Ã(1)Πu-X̃(1)Σ(+) g transition of C3 and form two close pairs, each consisting of a type A and a type C band of an asymmetric top, about 4 cm(-1) apart. Only K″ = even lines are found, showing that the complex has two equivalent carbon atoms (I = 0), and must be T-shaped, or nearly so. Strong a- and b-axis electronic-rotational (Coriolis) coupling occurs between the upper states of a pair, since they correlate with a (1)Πu vibronic state of C3, where the degeneracy is lifted in the lower symmetry of the complex. Least squares rotational fits, including the coupling, have given the rotational constants for both electronic states: the van der Waals bond lengths are 3.81 and 3.755 Å, respectively, in the ground and excited electronic states. For the ground state our new quantum chemical calculations, using the Multi-Channel Time-Dependent Hartree method, indicate that the C3 unit is non-linear, and that the complex does not have a rigid-molecule structure, existing instead as a superposition of arrowhead (↑) and distorted Y-shaped (Y) structures.
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Affiliation(s)
- Anthony J Merer
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10617, Taiwan
| | - Yen-Chu Hsu
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10617, Taiwan
| | - Yi-Ren Chen
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10617, Taiwan
| | - Yi-Jen Wang
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10617, Taiwan
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Sych Y, Bornhauser P, Knopp G, Liu Y, Gerber T, Marquardt R, Radi PP. Perturbation facilitated two-color four-wave-mixing spectroscopy of C3. J Chem Phys 2014; 139:154203. [PMID: 24160506 DOI: 10.1063/1.4825198] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Perturbation-facilitated two-color resonant four-wave-mixing spectroscopy is realized to access the (dark) triplet manifold of the C3 molecule from the singlet X̃(1)Σg (+) ground state. The inherent nonlinear signal dependence and coherence of the technique result in a favorable detection of the excited triplet states of interest. The observation of a newly found (3)Δu electronic state is achieved by a two-step excitation via "gate-way" levels (i.e., singlet-triplet mixed levels). Additionally, by fixing the probe laser on a transition exhibiting mainly triplet-triplet character and scanning the pump laser, we demonstrate an effective spin-filtering in a four-wave mixing measurement where only transitions to the perturber (3)Σu(-) state appear exclusively in an otherwise congested spectral range of the Comet band. Ab initio calculations of excited triplet states complement our analysis with the electronic assignment of the observed resonances.
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Affiliation(s)
- Y Sych
- Department General Energy Research, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
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Wang YJ, Chen CW, Zhou L, Merer AJ, Hsu YC. Fluorescence lifetimes of the Ã1Πu state of C3. J Phys Chem A 2013; 117:13878-84. [PMID: 24156666 DOI: 10.1021/jp408490d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The fluorescence lifetimes of 115 vibrational levels of the Ã1Π(u) state of C3 have been measured under supersonic molecular beam conditions. Of these, ninety-one are Π(u) vibronic levels, for which the lifetimes lie in the range 190-700 ns. The lifetimes of those Π(u) levels where only the bending vibration is excited lie in the range 190-235 ns. There is very little variation with bending quantum number, and the lifetimes of the two orbital components of the 1Π(u) state are essentially the same. When ν1 and ν3 are excited, the lifetimes become longer and/or reach a maximum for levels with v1 + v3 ~ 4. Excitation of the bending vibration in addition to the stretching vibrations shortens the lifetime slightly. Several of the levels show double-exponential decays. Another 23 levels, of Σ(u)+ vibronic symmetry, mostly have lifetimes that are longer than 300 ns. Interaction with nearby "dark" electronic states, such as B1Σ(u)-, B'1Δ(u), C1Π(g), and b3Π(g), is proposed to account for the observed lifetime lengthening. A particularly clear instance of such an interaction is the long lifetime (914 ns) of a perturbing Σ(u)+ level at 30,181 cm(-1), which is confirmed as belonging to the perturbing B'1Δ(u) state. A single level of Δ(u) symmetry at 29,170 cm(-1), which perturbs one of the Π(u) levels, is shown to belong to the à state.
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Affiliation(s)
- Yi-Jen Wang
- Institute of Atomic and Molecular Sciences, Academia Sinica , P.O. Box 23-166, Taipei 10716, Taiwan, R. O. C
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Chao JM, Tham KS, Zhang G, Merer AJ, Hsu YC, Hu WP. The C3-bending vibrational levels of the C3-Kr and C3-Xe van der Waals complexes studied by their Ã-X̃ electronic transitions and by ab initio calculations. J Chem Phys 2011; 134:074313. [PMID: 21341850 DOI: 10.1063/1.3506635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Fluorescence excitation spectra and wavelength-resolved emission spectra of the C(3)-Kr and C(3)-Xe van der Waals (vdW) complexes have been recorded near the 2(2-)(0), 2(2+)(0), 2(4-)(0), and 1(1)(0) bands of the Ã(1)Π(u)-X̃(1)Σ(g)(+) system of the C(3) molecule. In the excitation spectra, the spectral features of the two complexes are red-shifted relative to those of free C(3) by 21.9-38.2 and 34.3-36.1 cm(-1), respectively. The emission spectra from the à state of the Kr complex consist of progressions in the two C(3)-bending vibrations (ν(2), ν(4)), the vdW stretching (ν(3)), and bending vibrations (ν(6)), suggesting that the equilibrium geometry in the X̃ state is nonlinear. As in the Ar complex [Zhang et al., J. Chem. Phys. 120, 3189 (2004)], the C(3)-bending vibrational levels of the Kr complex shift progressively to lower energy with respect to those of free C(3) as the bending quantum number increases. Their vibrational structures could be modeled as perturbed harmonic oscillators, with the dipole-induced dipole terms of the Ar and Kr complexes scaled roughly by the polarizabilities of the Ar and Kr atoms. Emission spectra of the Xe complex, excited near the Ã, 2(2-) level of free C(3), consist only of progressions in even quanta of the C(3)-bending and vdW modes, implying that the geometry in the higher vibrational levels (υ(bend) ≥ 4, E(vib) ≥ 328 cm(-1)) of the X̃ state is (vibrationally averaged) linear. In this structure the Xe atom bonds to one of the terminal carbons nearly along the inertial a-axis of bent C(3). Our ab initio calculations of the Xe complex at the level of CCSD(T)∕aug-cc-pVTZ (C) and aug-cc-pVTZ-PP (Xe) predict that its equilibrium geometry is T-shaped (as in the Ar and Kr complexes), and also support the assignment of a stable linear isomer when the amplitude of the C(3) bending vibration is large (υ(4) ≥ 4).
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Affiliation(s)
- Jun-Mei Chao
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
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Saha S, Western CM. Experimental and ab initio study of a new D 1Deltag state of the C3 radical. J Chem Phys 2007; 125:224307. [PMID: 17176141 DOI: 10.1063/1.2399528] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We report here the first observation of the D (1)Delta(g) state of the C(3) radical, which provides the first comprehensively analyzed example of the dynamic Renner-Teller splitting in Delta symmetry. Two color double resonance spectroscopy via the A (1)Pi(u) state was employed to experimentally probe an extensive range of vibronic levels in this D (1)Delta(g) state, covering all three modes of vibration of C(3). The analysis was supported by ab initio potential energy surface calculations on the C(3) radical to outline the lowest eight singlet electronic states. Two methods were used to analyze the Renner-Teller effect. The first method is an empirical Hamiltonian based on normal modes, using harmonic oscillator functions as a basis, with Renner-Teller and other terms added as required, which allows conventional vibrational parameters to be determined. The second is a much larger program that uses the exact kinetic energy operator for a triatomic molecule to calculate vibronic energy levels directly from the Renner-Teller pair of potential energy surfaces. Both methods give a good fit to the experimental results, with only a small adjustment to the ab initio surfaces required for the latter. One of the overall conclusions is that the Renner-Teller effect is rather smaller in the D (1)Delta(g) state than in the A (1)Pi(u) state.
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Affiliation(s)
- Sudarshana Saha
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
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Boguslavskiy AE, Maier JP. Gas phase electronic spectra of the carbon chains C5, C6, C8, and C9. J Chem Phys 2006; 125:094308. [PMID: 16965081 DOI: 10.1063/1.2276848] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Three electronic absorption systems for C5 at 511, 445, and 232 nm and one for C6, C8, and C9 centered at 228, 259, and 288 nm have been observed in the gas phase. The C5 chain was produced in both discharge and ablation sources and detected using resonant two-color two-photon ionization spectroscopy involving 10.5 eV photons. The decay of the excited singlet electronic states indicates fast intramolecular processes on a subpicosecond time scale. The internal energy is assumed to be trapped in a triplet state for at least 15 micros. Hole-burning experiments on the 2 (3)Sigma(u)- <-- X (3)Sigma(g)- transition of C6, C8, and (1)Sigma(u)+ <-- X (1)Sigma(g)+ of C9 confirm the predissociative nature of the excited electronic states.
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Affiliation(s)
- A E Boguslavskiy
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.
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