| 1. |
- Chen, Fuqiang, et al.
(författare)
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Radiative cooling of cationic carbon clusters, CN+, N=8,10,13-16
- 2019
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Ingår i: Physical Chemistry Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 21, s. 1587-1596
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Tidskriftsartikel (refereegranskat)abstract
- The radiative cooling of highly excited carbon cluster cations of sizes N = 8, 10, 13–16 has been studied in an electrostatic storage ring. The cooling rate constants vary with cluster size from a maximum at N = 8 of 2.6 × 104 s−1 and a minimum at N = 13 of 4.4 × 103 s−1. The high rates indicate that photon emission takes place from electronically excited ions, providing a strong stabilizing cooling of the molecules.
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| 2. |
- Goto, Motoshi, et al.
(författare)
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Direct observation of internal energy distributions of C5-
- 2013
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 139:5
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Tidskriftsartikel (refereegranskat)abstract
- Photon induced decay of C5- has been measured in an electrostatic storage ring. The time dependence of the photo-enhanced decay is close to a 1/t decay which indicates a thermal process. The deviation from the expected power of −1 is quantitatively explained by the small heat capacity of the anion. Measurements of the photo-enhanced decay at different storage times and photon energies allow a determination of the radiative cooling rate and the energy distribution of the ions. The average energy content between 15 and 70 ms is found to vary as time to the power −0.72, and at 50 ms the ions contain an average excitation energy of 0.5 eV. The time dependent energy distribution is consistent with cooling by infrared photon emission if published oscillator strengths are reduced by a factor 2.5, in contrast to cooling of larger molecular carbon-based ions where electronic transitions cause a much stronger cooling.
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| 3. |
- Hansen, Klavs, 1958, et al.
(författare)
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Detection of Recurrent Fluorescence Photons
- 2016
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 117
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Tidskriftsartikel (refereegranskat)abstract
- We have detected visible photons emitted from the thermally populated electronic excited state, namely recurrent fluorescence (RF), of C−6 stored in an electrostatic ion storage ring. Clear evidence is provided to distinguish RF from normal fluorescence, based on the temporal profile of detected photons synchronized with the revolution of C−6 in the ring, for which the time scale is far longer than the lifetime of the intact photoexcited state. The relaxation (cooling) process via RF is likely to be commonplace for isolated molecular systems and crucial to the stabilization of molecules in interstellar environments.
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| 4. |
- Ito, Gen, et al.
(författare)
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Difference in cooling dynamics between photo-excited C6- and C6H-
- 2014
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Ingår i: Journal of Physics, Conference Series. - 1742-6588 .- 1742-6596. ; 488
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Tidskriftsartikel (refereegranskat)abstract
- Laser-induced electron detachment of C6- and C6H- stored in an ion storage ring was observed respectively, focusing attention onto the delayed processes with the time constants up to several milliseconds. We found the drastic difference in the decay profiles of photo-excited C6- and C6H- that is, C6- decayed much faster than C6H-. The unexpected fast decay of C6- indicates that it is governed by the radiative cooling with electronic transitions rather than vibrational nor depletion cooling.
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| 5. |
- Najafian, Kaveh, et al.
(författare)
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Radiative cooling of C7-
- 2014
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 140:10
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Tidskriftsartikel (refereegranskat)abstract
- The spontaneous and photo-induced neutralization of C_7- produced in a laser ablation source was measured in an electrostatic storage ring. The measurements provide three independent determinations of the radiative cooling of the ions, based on the short time spontaneous decay and on the integrated amplitude and the shape of the photo-induced neutralization signal. The amplitude of the photo-induced signal was measured between 0.5 ms and 35 ms and found to depend on photon wavelength and ion storage time. All three signals can be reproduced with identical thermal IR radiative cooling rates with oscillator strengths equal to theoretical predictions. In addition, the measurements provide the excitation energy distribution.
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