Spontaneous emission from the C3 radical in carbon plasma

Nemes, L.; Keszler, Ágnes; Parigger, Christian G.; Hornkohl, James O.; Michelsen, Hope A.; Stakhursky, Vadim

doi:10.1364/ao.46.004032

Cited by 31 publications

(18 citation statements)

References 33 publications

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“…The weakness of C 3 emissions in our spectra is somewhat surprising as it has been known for a long time that the C 3 radical is a dominant component of thermal equilibrium carbon vapors [29]. Some likely explanations for the weak emissions can be found by considering nonequilibrium conditions [30], electron collision cross-sections [31,32] and C 3 cation formation [33] and slow intersystem crossing from triplet C 3 to singlet C 3 [34] in laser ablation plasma.…”

Section: Discussion Of Experimentsmentioning

confidence: 84%

Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

Parigger

Hornkohl

Nemes

2010

International Journal of Spectroscopy

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Transient laser plasma is generated in laser-induced optical breakdown (LIOB). Here we report experiments conducted with 10.6-micron CO2 laser radiation, and with 1.064-micron fundamental, 0.532-micron frequency-doubled, 0.355-micron frequency-tripled Nd:YAG laser radiation. Characterization of laser induced plasma utilizes laser-induced breakdown spectroscopy (LIBS) techniques. Atomic hydrogen Balmer series emissions show electron number density of 1017 cm−3 measured approximately 10 μs and 1 μs after optical breakdown for CO2 and Nd:YAG laser radiation, respectively. Recorded molecular recombination emission spectra of CN and C2 Swan bands indicate an equilibrium temperature in excess of 7000 Kelvin, inferred for these diatomic molecules. Reported are also graphite ablation experiments where we use unfocused laser radiation that is favorable for observation of neutral C3 emission due to reduced C3 cation formation. Our analysis is based on computation of diatomic molecular spectra that includes accurate determination of rotational line strengths, or Hönl-London factors.

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Section: Discussion Of Experimentsmentioning

confidence: 84%

Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

Parigger

Hornkohl

Nemes

2010

International Journal of Spectroscopy

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“…Emission of 40 nm diameter particles reaches a maximum at near 550-600 nm [16]. There are two other sources, which could contribute to the observed continuum, either linear carbon molecules (C n with n≥4) or PAHs.…”

Section: Plasma Emission Spectroscopymentioning

confidence: 99%

Decomposition of Chlorobenzene by Thermal Plasma Processing

Fazekas

Bódis

Keszler

et al. 2013

Plasma Chem Plasma Process

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Decomposition of chlorobenzene as a model molecule of aromatic chlorinated compounds was studied in radiofrequency (RF) thermal plasma both in neutral and oxidative conditions. Optical emission spectroscopy (OES) was applied for the evaluation of the plasma excitation and molecular rotational-vibrational temperature. Atomic (C, H, O) and molecular (CH, OH, C 2 ) radicals were identified, while the morphology of the formed soot was characterized by electron microscopy. Organic compounds adsorbed on the surface of the soot after plasma processing were comprised of various polycyclic aromatic hydrocarbons (PAH) and chlorinated PAH molecules. Their amount was greatly affected by experimental conditions, especially the oxygen content and plate power. The higher input power reduced the ring number of the PAH molecules. Addition of oxygen significantly reduced the amount of both PAHs chlorinated PAH molecules but enhanced the formation of polychlorinated benzene compounds.

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“…23 C 3 is also the predominant carbon cluster in equilibrium hot carbon vapor, 19,24 hydrocarbon flames, 2,19 and plasmas generated through energetic processing of carbon containing materials. 19,25,26 The relevance of the C 3 molecule in space 27 as well as in terrestrial sooting flames and combustion processes 2,19 has motivated many experimental [28][29][30] and theoretical 17,18,[31][32][33][34][35][36][37][38][39][40][41] ) electronic manifolds. 23,[38][39][40] It is worth pointing out that, from the theoretical perspective, much effort has been devoted to obtain local (near-equilibrium) ground state potential energy surfaces 42 (PESs) for C 3 aiming to explore its spectroscopy, notably the unusual large amplitude bending motion and related speculations concerning its quasi-linearity (for a comprehensive review, see Refs.…”

Section: Introductionmentioning

confidence: 99%

Accurate ab initio-based double many-body expansion potential energy surface for the adiabatic ground-state of the C3 radical including combined Jahn-Teller plus pseudo-Jahn-Teller interactions

Rocha

Varandas

2015

The Journal of Chemical Physics

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A fully ab initio-based potential energy surface is first reported for the ground electronic state of the C3 radical using the double many-body expansion (DMBE) method. The DMBE form so obtained mimics the full set of energies calculated at the multireference configuration interaction level of theory with chemical accuracy. To account for the incompleteness of the one- and N-electron bases, the calculated external correlation energies have been scaled prior to the fitting procedure via DMBE-scaled external correlation method. Furthermore, the novel potential energy surface reproduces accurately dissociation energies, diatomic potentials, long-range interactions at all asymptotic channels, and the correct topological behavior at the region of 4 conical intersections with the partner state of the same symmetry near equilateral triangular geometries due to combined Jahn-Teller (E' ⊗ e') plus pseudo-Jahn-Teller [(E'+A1')⊗e'] interactions. Rovibrational calculations have also been performed, unveiling a good match of the vibrational spectrum of C3 for 53 calculated levels. The present DMBE form is, therefore, commended for both spectroscopic and reaction dynamics studies, some also performed in the present work.

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Spontaneous emission from the C3 radical in carbon plasma

Cited by 31 publications

References 33 publications

Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

Time-Resolved Spectroscopy Diagnostic of Laser-Induced Optical Breakdown

Decomposition of Chlorobenzene by Thermal Plasma Processing

Accurate ab initio-based double many-body expansion potential energy surface for the adiabatic ground-state of the C3 radical including combined Jahn-Teller plus pseudo-Jahn-Teller interactions

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