Statistical vibrational autodetachment and radiative cooling rates of <i>para</i>-benzoquinone

Stockett, Mark H.; Bull, James N.; Schmidt, H. T.; Zettergren, Henning

doi:10.1039/d2cp00490a

Cited by 6 publications

(6 citation statements)

References 43 publications

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“…Even though this limit is above the adiabatic detachment threshold (EA = 1.096 eV), the autodetachment rate at T ≈ 700 K is expected to be low (and, in fact, not observed in the photoelectron images in Figure ). Vibrational autodetachment requires more than EA of energy to be channeled in the electronic degrees of freedom, which is statistically unlikely due to the thermal excitation energy being partitioned among many vibrations. − …”

Section: Statistical Approach To Hot-ion Spectramentioning

confidence: 99%

Photoelectron Spectra of Hot Polyatomic Ions: A Statistical Treatment of Phenide

Sanov

2022

J. Phys. Chem. A

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Many distinct vibrational states contribute to the congested photoelectron spectra of hot polyatomic anions. This often makes the complete Franck−Condon (FC) analysis both impractical and unnecessary. Although it is common to limit the FC calculations to a subset of the FC-active modes, such a limited approach is strictly applicable to the ground-state (cold) anions only. At high temperatures, all vibrational modes participate in thermal excitation, and the FC and thermal activities become intertwined. We report the photoelectron spectra of ∼700 K phenide (C 6 H 5 − ) obtained at 355 nm (3.49 eV), 532 nm (2.33 eV), and 611 nm (2.03 eV) and describe several practical models that help interpret and analyze the results. Among them are the active-modes model, the active modes + dark bath and the active modes + bright bath models, and, finally, the energy-conservation model. The models combine the results of limited (and, therefore, feasible) FC calculations with statistical analysis and provide efficient means of determining the ion temperature from the broad and congested photoelectron spectra. The described capability can be applied to hot plasmas, the collisional excitation or cooling of ions, and evaporative cooling in cluster ions.

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Section: Statistical Approach To Hot-ion Spectramentioning

confidence: 99%

Photoelectron Spectra of Hot Polyatomic Ions: A Statistical Treatment of Phenide

Sanov

2022

J. Phys. Chem. A

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“…2) has been observed previously for other PAHs, and has been attributed to sequential fragmentation of ionic products close enough in mass to the precursor to remain stored in the ring. 27 An alternative hypothesis is that the simple statistical model of RF (Eq. 17), which was first proposed by Boissel et al 8 does not fully capture the photophysics of RF in PAHs.…”

Section: Discussionmentioning

confidence: 99%

“…22,23 Electrostatic ion storage devices feature sampling times exceeding 1 s, orders of magnitude longer than conventional mass spectrometers, enabling time-resolved observations of delayed processes such as unimolecular dissociation 16 and thermionic electron emission. 24 DESIREE has also been used for vibrational energy dependent action spectroscopy of astrophyscially relevant ions including PAHs, 25,26 substituted PAHs thought to form in interstellar ices, 27,28 and carbon cluster anions. 29,30 The methods used here have largely been described previously.…”

Section: Methodsmentioning

confidence: 99%

Experimental radiative cooling rates of a polycyclic aromatic hydrocarbon cation

et al. 2023

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“…Note that the exponential quenching of the decay rate is not due to loss of stored ion current due to residual gas collisions. The collision-limited lifetimes of molecular ion beams in DESIREE are measured in hundreds of seconds 10,[38][39][40] , five orders of magnitude longer than typical values of k −1 c . On the other hand, k −1 c is typically orders of magnitude longer than the revolution period of the ions around the ring.…”

Section: Dissociation Ratesmentioning

confidence: 96%

Radiative cooling rates of substituted PAH ions

Zhu

Bull

et al. 2022

The Journal of Chemical Physics

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The unimolecular dissociation and infrared radiative cooling rates of cationic 1-hydroxypyrene (OHPyr$^+$, \ce{C16H10O+}) and 1-bromopyrene (BrPyr$^+$, \ce{C16H9Br+}) are measured using a cryogenic electrostatic \rev{ion beam} storage ring. A novel numerical approach is developed to analyze the time dependence of the dissociation rate and to determine the absolute scaling of the radiative cooling rate coefficient. The model results show that radiative cooling competes with dissociation below the critical total vibrational energies \revv{$E_c=5.39(1)$}~eV for OHPyr$^+$ and \revv{5.90(1)}~eV for BrPyr$^+$. These critical energies and implications for radiative cooling dynamics are important for astrochemical models concerned with energy dissipation and molecular lifecycles. The methods presented extend the utility of storage ring experiments on astrophysically relevant ions.

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Statistical vibrational autodetachment and radiative cooling rates of para-benzoquinone

Abstract: We report measurements of the statistical vibrational autodetachment (VAD, also called thermionic emission) and radiative cooling rates of isolated \textit{para}-benzoquinone (\textit{p}BQ, \ce{C6H4O2}) radical anions using the cryogenic electrostatic ion storage...

Cited by 6 publications

References 43 publications

Photoelectron Spectra of Hot Polyatomic Ions: A Statistical Treatment of Phenide

Photoelectron Spectra of Hot Polyatomic Ions: A Statistical Treatment of Phenide

Experimental radiative cooling rates of a polycyclic aromatic hydrocarbon cation

Radiative cooling rates of substituted PAH ions

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