Thermal radiative cooling of carbon cluster cations CN+, <i>N</i> = 9, 11, 12, 17–27

ABSTRACT The radiative cooling rates of C$_N^+$ clusters (N = 9, 11, 12, 17–27) have been measured in the ultrahigh vacuum an electrostatic storage ring to values on order 104 s?1. were as a competing channel unimolecular decay, and rate constants pertain excitation energies where these two channels compete. Such high can only be explained photon emission from thermally excited electronic states, mechanism that has also seen polycyclic aromatic hydrocarbon cations. very strong stabilizing effect underlying gives energy conversion efficiency, with potential reach quantum efficiencies process. decay fragmentation defines upper limits for down-converted lower photons. Including previously cluster sizes provides all C$_N^+$, N 8–27, vary 10 14.5 eV, general increase size. Clusters absorbing photons below cool down efficiently by via transitions their is strongly reduced, increasing survival HI regions.