Cooling of Molecular Ions by Recurrent Fluorescence

When hot molecular ions are isolated in vacuum, they cool solely by radiative processes. Recent experiments using electrostatic ion storage rings deepen the understanding of such slow processes.We will show how the electronic transi-tion triggered by the inverse internal conversion works in the even-numbered carbon cluster anions.Theoretical frame-work for estimating the radiative cooling rates, vibrational and electronic, is briefly introduced.