Delayed ionization of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mrow><mml:mn>60</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mrow><mml:mn>70</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Campbell, Eleanor E. B.; Ulmer, Gene C.; Hertel, I. V.

doi:10.1103/physrevlett.67.1986

Cited by 201 publications

(94 citation statements)

References 10 publications

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“…2, results from statistical electron emission from the ground electronic state of C 18 H 11 -. 26,[33][34][35][36][37] That is, excess internal energy statistically accumulates amongst certain modes leading to ejection of the most weakly bound electron. The properties, typical lifetimes (micro-to milliseconds), and mathematical description of thermionic emission have been well-reviewed in the aforementioned references.…”

Section: Thermionic Emissionmentioning

confidence: 99%

“…31,32 If such an anion is formed under isolated conditions, the total internal energy of the system remains above the neutral ground state and the system may statistically detach the most weakly bound electron on a microsecond to millisecond timescale -known as thermionic emission. [33][34][35][36][37] Alternatively, some internally-hot anions may liberate excess internal energy through photoemission processes or by unimolecular dissociation to yield a stable anion.Using pump-probe femtosecond spectroscopy we have recently shown that a conjugated quinone, menadione, 26 can very efficiently produce ground electronic state anions following photoexcitation (or electron capture) with energies up to 3 eV above-threshold and probably higher. In menadione, the , is partly for experimental reasons and because the electron affinity is larger while maintaining a similar π-system.…”

mentioning

confidence: 99%

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Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum

Bull

West

Verlet

2015

Phys. Chem. Chem. Phys.

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Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuumJames N. Bull a , Christopher W. West a and Jan R. R. Verlet a † Photoelectron velocity-map imaging and electronic structure calculations have been used to study the temporary anion (resonance) dynamics of the closed-shell site-specific deprotonated tetracene anion (C18H11 -) in the hv = 3.26 eV (380 nm) to 4.13 eV (300 nm) range. In accord with a recent frequency-, angle-, and time-resolved photoelectron imaging study on a related but open-shell polyaromatic radical anion (Chem. Sci., 2015, 6, 1578-1589, population of π*-resonances situated in the detachment continuum efficiently recover the ground electronic state of the anion through ultrafast non-adiabatic dynamics, followed by characteristic statistical electron loss (thermionic emission). The combined electron yield of direct photodetachment and autodetachment from the optically-accessed resonances in C18H11 -is several orders of magnitude smaller than thermionic emission from the ground electronic electronic state in the photon energy range studied. This result implies a resiliance to prompt photoejection from UV radiation, and the ability of neutral PAH-like species to capture a free electron and form a long-lived molecular anion that ultimately decays by thermionic emission on a millisecond timescale. The attachment mechanism applies to polyaromatic species that cannot support dipole-bound states, and may provide an additional route to forming anions in astrochemical environments. IntroductionPolyaromatic hydrocarbon (PAH) molecules are found across a diverse range of chemical environments. For example, they form as products in combustion and anthropogenic pollution, 1 they are used in new generation semiconductors and microelectronics, 2,3 and they have been postulated to be present in astrochemical environments. 4,5 In astrochemistry, anions are recognised as important chemical species, [6][7][8][9][10][11] and have been identified as small polyynes such as C 4 H -and C 6 H -, [12][13][14][15][16][17][18] and are commonly postulated to be present as PAHs. However, the detailed formation mechanism of astrochemical anions is unclear. It is commonly postulated that stable anions may be formed via electric dipole-bound doorway states; 19,20 however, most neutral PAH molecules do not have a sufficient dipole moment to support such a mechanism.Most molecules,...

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Section: Thermionic Emissionmentioning

confidence: 99%

mentioning

confidence: 99%

Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum

Bull

West

Verlet

2015

Phys. Chem. Chem. Phys.

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“…Internal energies up to tens of eV, corresponding to temperatures of thousands of K, can be achieved by absorption of many photons and rapid conversion from electronic to vibrational excitation. These superheated neutral molecules are observed to undergo delayed ionization [2,3], fragmentation [4], and optical emission [5], the microscopic analogs of well-known macroscopic cooling processes like thermionic emission, evaporation, and blackbody emission, respectively [1]. Detection of superheated neutral C 60 via delayed ionization becomes very efficient once the internal energy reaches 35 -40 eV [1].…”

Section: Infrared Resonance Enhanced Multiphoton Ionization Of Fullermentioning

confidence: 99%

Infrared Resonance Enhanced Multiphoton Ionization of Fullerenes

et al. 1997

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“…In addition, delayed ionization sets in. 23 In the present work we report on a systematic two-color pump-probe mass-spectrometric study of the characteristic time scales involved in the ionization and fragmentation dynamics of C 60 fullerenes. The basic idea is to mimic the effect of elongated pulses by a femtosecond pump-probe approach with variable time delay between the pulses.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast energy redistribution in C60 fullerenes: A real time study by two-color femtosecond spectroscopy

Shchatsinin

Laarmann

Zhavoronkov

et al. 2008

The Journal of Chemical Physics

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Strong-field excitation and energy redistribution dynamics of C 60 fullerenes are studied by means of time-resolved mass spectrometry in a two-color femtosecond pump-probe setup. Resonant pre-excitation of the electronic system via the first dipole-allowed HOMO→ LUMO+ 1͑t 1g ͒ ͑HOMO denotes highest occupied molecular orbital and LUMO denotes lowest unoccupied molecular orbital͒ transition with ultrashort 25 fs pulses at 399 nm of some 10 12 W cm −2 results in a highly nonequilibrium distribution of excited electrons and vibrational modes in the neutral species. The subsequent coupling among the electronic and nuclear degrees of freedom is monitored by probing the system with time-delayed 27 fs pulses at 797 nm of some 10 13 W cm −2 . Direct information on the characteristic relaxation time is derived from the analysis of transient singly and multiply charged parent and fragment ion signals as a function of pump-probe delay and laser pulse intensity. The observed relaxation times el Ӎ 60-400 fs are attributed to different microcanonical ensembles prepared in the pre-excitation process and correspond to different total energy contents and energy sharing between electronic and vibrational degrees. The characteristic differences and trends allow one to extract a consistent picture for the formation dynamics of ions in different charge states and their fullerenelike fragments and give evidence to collective effects in multiple ionization such as plasmon-enhanced energy deposition.

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Delayed ionization ofC60andC70

Abstract: Delayed ionization with average lifetimes on the order of several //sec has been observed for twophoton 308-nm excimer laser ionization of C60 and C70.

Cited by 201 publications

References 10 publications

Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum

Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum

Infrared Resonance Enhanced Multiphoton Ionization of Fullerenes

Ultrafast energy redistribution in C60 fullerenes: A real time study by two-color femtosecond spectroscopy

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