Cooling dynamics of carbon cluster anions

Shiromaru, H.; Furukawa, T.; Ito, Gen; Kono, Naoko; Tanuma, H.; Matsumoto, Jun; Goto, M.; Majima, T.; Sundén, A. E. K.; Najafian, Kaveh; Pettersson, Maria Susanne; Dynefors, Bertil; Hansen, Klavs; Azuma, T.

doi:10.1088/1742-6596/635/1/012035

Cited by 3 publications

(3 citation statements)

References 18 publications

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“…≈2-3 eV) followed by radiative emission. 26 • Slow regime II (t ≈10 −3 -1 s): Internal energy is in the vicinity of the lowest thresholds for the cooling mechanisms important for Regime I, e.g. ∼2 eV.…”

Section: Introductionmentioning

confidence: 99%

Ultraslow radiative cooling of Cn− (n = 3–5)

Bull

Scholz

Carrascosa

et al. 2019

The Journal of Chemical Physics

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Ultraslow radiative cooling lifetimes and adiabatic detachment energies for three astrochemically relevant anions, C − n (n = 3 − 5), are measured using the Double ElectroStatic Ion Ring ExpEriment (DESIREE) infrastructure at Stockholm University. DESIREE maintains a background pressure of ≈10 −14 mbar and temperature of ≈13 K, allowing storage of mass-selected ions for hours and providing conditions coined a "molecular cloud in a box". Here, we construct two-dimensional (2D) photodetachment spectra for the target anions by recording photodetachment signal as a function of irradiation wavelength and ion storage time (seconds to minute timescale). Ion cooling lifetimes, which are associated with infrared radiative emission, are extracted from the 2D photodetachment spectrum for each ion by tracking the disappearance of vibrational hot-band signal with ion storage time, giving 1 e cooling lifetimes of 3.1±0.1 s (C − 3 ), 6.8±0.5 s (C − 4 ) and 24±5 s (C − 5 ). Fits of the photodetachment spectra for cold ions, i.e. those stored for at least 30 s, provides adiabatic detachment energies in good agreement with values from laser photoelectron spectroscopy. Ion cooling lifetimes are simulated using a Simple Harmonic Cascade model, finding good agreement with experiment and providing a mode-by-mode understanding of the radiative cooling properties. The 2D photodetachment strategy and radiative cooling modeling developed in this study could be applied to investigate the ultraslow cooling dynamics of wide range of molecular anions. arXiv:1909.07087v1 [physics.atm-clus]

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Section: Introductionmentioning

confidence: 99%

Ultraslow radiative cooling of Cn− (n = 3–5)

Bull

Scholz

Carrascosa

et al. 2019

The Journal of Chemical Physics

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“…Relaxation proceeds subsequently through emission of IR photons (vibrational emission), 38,39 in competition with fragmentation and isomerization if these pathways are open at the available internal energy. In the case of carbon cluster ions, radiative cooling has been specifically investigated in the size range of 36-96 atoms, [40][41][42][43][44][45] in smaller carbon clusters [46][47][48][49][50][51] and perylene cation as well, 52 especially by means of electrostatic storage rings. However, it is also possible that a part of the vibrational energy flows back into the electronic degrees of freedom, especially if there are some low-lying electronic excited states as in the case of carbon clusters.…”

Section: Introductionmentioning

confidence: 99%

Radiative relaxation in isolated large carbon clusters: Vibrational emission versus recurrent fluorescence

Lacinbala

Calvo

Dubosq

et al. 2022

The Journal of Chemical Physics

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Recurrent fluorescence (RF) from isolated carbon clusters containing between 24 and 60 atoms is theoretically investigated as a function of internal energy, cluster size, and structural features. The vibrational relaxation kinetics and the associated IR emission spectra are determined by means of a Monte Carlo approach with vibrational density of states computed in the harmonic approximation. RF is generally found to be highly competitive with vibrational emission. The behaviors predicted for clusters of various sizes and archetypal structures indicate that the IR emission spectra are strongly influenced by RF, an energy gap law being obtained for the evolution of the RF rate constant depending on the electronic excitation state. The present results are relevant to the photophysics of the interstellar medium and could contribute to elucidating the carriers of the extended red emission bands and the continuum emission lying below the aromatic infrared bands believed to originate from mixed aromatic–aliphatic compounds.

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“…This power law decay is caused by a broad distribution of decay constants, most often produced by a close-to-uniform distribution of internal excitation energies of the stored ions [11]. Since then, power law decays have been reported for many different types of charged polyatomic systems including metal clusters [12][13][14][15][16], fullerenes [17,18], small carbon and hydrocarbon molecules [19][20][21], biomolecules [22][23][24], Polycyclic Aromatic Hydrocarbons (PAHs) [25,26], and SF − 6 [27,28]. In many of these cases, deviations from a pure t −1 decay have been observed.…”

Section: Introductionmentioning

confidence: 99%

Decays of excited silver-cluster anions Agn , n=4 to 7, in the Double ElectroStatic Ion Ring ExpEriment

et al. 2018

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Spontaneous decays of small, hot silver cluster anions Ag − n n = 4 − 7 have been studied using one of the rings of the Double ElectroStatic Ion Ring ExpEriment (DESIREE). Observation of these decays over very long time scales is possible due to the very low residual gas pressure (∼ 10 −14 ) and cryogenic (13 K) operation of DESIREE. The yield of neutral particles from stored beams of Ag − 6 and Ag − 7 anions were measured for 100 milliseconds and were found to follow single power law behaviour with millisecond time scale exponential cut-offs. The Ag − 4 and Ag − 5 anions were stored for 60 seconds and the observed decays show two-component power law behaviors. We present calculations of the rate constants for electron detachment from, and fragmentation of Ag − 4 and Ag − 5 . In these calculations, we assume that the internal energy distribution of the clusters are flat and with this we reproduce the early steep parts of the experimentally measured decay curves for Ag − 4 and Ag − 5 , which extends to tens and hundreds of milliseconds, respectively. The fact that the calculations reproduce the early slopes of Ag − 4 and Ag − 5 , which differ for the two cases, suggests that it is the changes in fragmentation rates with internal cluster energies of Ag − 4 and Ag − 5 rather than conditions in the ion source that determines this behavior. Comparisons with the measurements strongly suggest that the neutral particles detected in these time domains originate from Ag − 4 →Ag − 3 + Ag and Ag − 5 →Ag − 3 + Ag2 fragmentation processes. arXiv:1805.12437v1 [physics.atm-clus] 31 May 2018

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Cooling dynamics of carbon cluster anions

Cited by 3 publications

References 18 publications

Ultraslow radiative cooling of Cn− (n = 3–5)

Ultraslow radiative cooling of Cn− (n = 3–5)

Radiative relaxation in isolated large carbon clusters: Vibrational emission versus recurrent fluorescence

Decays of excited silver-cluster anions Agn , n=4 to 7, in the Double ElectroStatic Ion Ring ExpEriment

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