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Mardi 27 novembre 2018 - 14:00

Recurrent Fluorescence Radiative Cluster Cooling

Klavs Hansen (Université de Tianjin, Chine)

par Revaz Ramazashvili - 27 novembre 2018

Interest in radiative cooling of free clusters and gas phase molecules has grown after it was realized that photons may be emitted with very high rates form thermally populated excited electronic states. The radiation, known as Poincaré radiation and recurrent fluorescence, has now been measured with time constants approaching one microsecond, more than three orders of magnitude faster than typical vibrational emission times. The high rates are a result of the large oscillator strength of the excited states. At the same time the populations of the electronic transitions are suppressed by entropic factors, and the precise rate constants depend critically on the balance between these two factors. This makes the presence or absence of this type of radiation a very sensitive probe of the low-lying states that are otherwise out of reach of spectroscopic methods.

In the talk I will give the background for the experimental observations of recurrent fluorescence, and present results on small charged carbon and gold clusters.

Références :

[1] G. Ito, et al., Phys. Rev. Lett. 112,183001 (2014).

[2] K. Hansen, et al., Phys. Rev. A 95, 022511 (2017).

Post-scriptum :

Contact : M. Dinh Phuong, E. Suraud