Production of jet-cooled coronene and coronene cluster anions and their study with photoelectron spectroscopy

Duncan, M. A.; Knight, A.M.; Negishi, Yuichi; Nagao, Shigeaki; Nakamura, Yoshiaki; Kato, Akiko; Nakajima, Atsushi; Kaya, Kunimitsu

doi:10.1016/s0009-2614(99)00662-4

Cited by 63 publications

(46 citation statements)

References 28 publications

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“…value of 7.29 ± 0.03 eV from the photoionisation threshold; 70 (ii) our estimates of the adiabatic electron affinity (0.29 eV) also reasonably agree with respect to available experimental values (0.47 ± 0.09). 71 We now turn to the discussion of reorganization energies of these molecules upon arrival of the hole or electron particles, with the calculated values also gathered in Table I. For the coronene case, we calculate rather similar values for both e ·− (144 meV) and h ·+ (189 meV), giving a ratio h ·+ / e ·− equal to 0.76 and thus close to ambipolar behavior, remaining the same other features.…”

Section: Structure and Frontier Orbitalsmentioning

confidence: 57%

Theoretical study of stability and charge-transport properties of coronene molecule and some of its halogenated derivatives: A path to ambipolar organic-based materials?

Sancho‐García

Pérez-Jiménez

2014

The Journal of Chemical Physics

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We have carefully investigated the structural and electronic properties of coronene and some of its fluorinated and chlorinated derivatives, including full periphery substitution, as well as the preferred orientation of the non-covalent dimer structures subsequently formed. We have paid particular attention to a set of methodological details, to first obtain single-molecule magnitudes as accurately as possible, including next the use of modern dispersion-corrected methods to tackle the corresponding non-covalently bound dimers. Generally speaking, this class of compounds is expected to self-assembly in neighboring π -stacks with dimer stabilization energies ranging from -20 to -30 kcal mol −1 at close distances around 3.0-3.3 Å. Then, in a further step, we have also calculated hole and electron transfer rates of some suitable candidates for ambipolar materials, and corresponding charge mobility values, which are known to critically depend on the supramolecular organization of the samples. For coronene and per-fluorinated coronene, we have found high values for their hopping rates, although slightly smaller for the latter due to an increase (decrease) of the reorganization energies (electronic couplings).

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Section: Structure and Frontier Orbitalsmentioning

confidence: 57%

Theoretical study of stability and charge-transport properties of coronene molecule and some of its halogenated derivatives: A path to ambipolar organic-based materials?

Sancho‐García

Pérez-Jiménez

2014

The Journal of Chemical Physics

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“…Regarding EAs, the first EA of C 24 H 12 is 0.47 eV, as derived from both theory and experiments (Duncan et al 1999;Malloci et al 2007). An et al (2008) reports an EA of 1.89 eV for C 24 , which agrees with the ∼0.1 eV variation per dehydrogenation derived from the IPs.…”

Section: Ionization Potentials and Electron Affinitiesmentioning

confidence: 72%

Hydrogenation and dehydrogenation of interstellar PAHs: Spectral characteristics and H₂formation

Andrews

Candian

Tielens

2016

A&A

117

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Context. We have modelled the abundance distribution and IR emission of the first 3 members of the coronene family in the north-west photodissociation region of the well-studied reflection nebulae NGC 7023. Aims. Our aim was 3-fold: i) analyze the distribution of abundances; (ii) examine the spectral footprints from the hydrogenation state of polycyclic aromatic hydrocarbons (PAHs); and (iii) assess the role of PAHs in the formation of H 2 in photodissociation regions. Methods. To model the physical conditions inside the cloud, we used the Meudon PDR Code, and we gave this as input to our kinetic model. We used specific molecular properties for each PAH, based on the latest data available at the present time. We considered the loss of an H atom or an H 2 molecule as multiphoton processes, and we worked under the premise that PAHs with extra H atoms can form H 2 through an Eley-Rideal abstraction mechanism. Results. In terms of abundances, we can distinguish clear differences with PAH size. The smallest PAH, coronene (C 24 H 12 ), is found to be easily destroyed down to the complete loss of all of its H atoms. The largest species circumcircumcoronene (C 96 H 24 ), is found in its normal hydrogenated state. The intermediate size molecule, circumcoronene (C 54 H 18 ), shows an intermediate behaviour with respect to the other two, where partial dehydrogenation is observed inside the cloud. Regarding spectral variations, we find that the emission spectra in NGC 7023 are dominated by the variation in the ionization of the dominant hydrogenation state of each species at each point inside the cloud. It is difficult to "catch" the effect of dehydrogenation in the emitted PAH spectra since, for any conditions, only PAHs within a narrow size range will be susceptible to dehydrogenation, being quickly stripped off of all H atoms (and may isomerize to cages or fullerenes). The 3 µm region is the most sensitive one towards the hydrogenation level of PAHs. Conclusions. Based on our results, we conclude that PAHs with extra H atoms are not the carriers of the 3.4 µm band observed in NGC 7023, since these species are only found in very benign environments. Finally, concerning the role of PAHs in the formation of H 2 in photodissociation regions, we find that H 2 abstraction from PAHs with extra H atoms is an inefficient process compared to grains. Instead, we propose that photodissociation of PAHs of small-to-intermediate sizes could contribute to H 2 formation in PDR surfaces, but they cannot account by themselves for the inferred high H 2 formation rates in these regions.

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“…Previous studies have reported observations of small PAH clusters up to the size of anthracene (Piuzzi et al 2002;Mitsui et al 2004, and references therein). Duncan et al (1999) have reported about the formation in a laser ablation puled nozzle source of coronene clusters made of a few coronene units. With such a source they were able to measure the electron affinity of (C 24 H 12 ) n for n = 1 to 3 ).…”

Section: Cold Coronene Cluster Distributionmentioning

confidence: 99%

Photoinduced products from cold coronene clusters

Bréchignac¹,

Schmidt

Masson

et al. 2005

A&A

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Free cold pure coronene clusters have been formed in a gas aggregation source and irradiated with excimer laser pulses. Analysis of the photoproducts thanks to a reflectron time-of-flight mass spectrometer showed that new ionic compounds are formed. These species may include Polycyclic Aromatic Hydrocarbons (PAHs) larger than coronene, PAH-coronene clusters, as well as coronene clusters branched with unsaturated aliphatic chains. The relevance of these results in the context of interstellar medium chemistry, and in particular the carriers of the so-called aromatic infrared emission bands (AIBs), is discussed.

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Production of jet-cooled coronene and coronene cluster anions and their study with photoelectron spectroscopy

Cited by 63 publications

References 28 publications

Theoretical study of stability and charge-transport properties of coronene molecule and some of its halogenated derivatives: A path to ambipolar organic-based materials?

Theoretical study of stability and charge-transport properties of coronene molecule and some of its halogenated derivatives: A path to ambipolar organic-based materials?

Hydrogenation and dehydrogenation of interstellar PAHs: Spectral characteristics and H₂formation

Photoinduced products from cold coronene clusters

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Production of jet-cooled coronene and coronene cluster anions and their study with photoelectron spectroscopy

Cited by 63 publications

References 28 publications

Theoretical study of stability and charge-transport properties of coronene molecule and some of its halogenated derivatives: A path to ambipolar organic-based materials?

Theoretical study of stability and charge-transport properties of coronene molecule and some of its halogenated derivatives: A path to ambipolar organic-based materials?

Hydrogenation and dehydrogenation of interstellar PAHs: Spectral characteristics and H2formation

Photoinduced products from cold coronene clusters

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Hydrogenation and dehydrogenation of interstellar PAHs: Spectral characteristics and H₂formation