Inverse internal conversion in C₄⁻ below the electron detachment threshold

Abstract

Inverse internal conversion followed by recurrent fluorescence was observed as a fast decay (10 μs range) in the time profile of neutral yields from photo-excited C4(-) molecular ions. We also elucidated the contribution of such electronic radiative cooling to the C4(-) ions with internal energy far below the detachment threshold by an alternative novel approach, observing the laser wavelength and storage time dependence (ms range) of the total yield of the photo-induced neutrals.

Thermal radiation of gold clusters on microsecond time scales

“…This type of radiation was proposed a long time ago [32,33] but was only recently detected for several excited carbon species [19,25,34,35] and very recently also confirmed by direct detection of emitted photons for C 6 − [36].…”

“…Irrespective of the precise magnitude of the emitted photon energy, k p can be set constant because the variation of that function is much slower than the other factors in the integrand, as mentioned (see also, e.g., [24,25]). This fact follows from the rigorous limits on the frequency factor for photon emission rate constants imposed by the dipole oscillator sum rules, given explicitly in Eq.…”

Detection of Recurrent Fluorescence Photons

“…C − 4 and C − 6 also possess low-lying electronic excited states [13][14][15], and the fast RF cooling of these species formed by electron attachment leads to efficient stabilization by quenching the thermal electron emission. Experimentally, the RF processes of the anthracene cations [16,17] and the small carbon cluster anions [18][19][20][21] have been recently identified, using ion storage rings and ion beam traps. These devices have enabled the study of radiative cooling processes of mass-selected and isolated molecular ions under ultrahigh vacuum conditions [22].…”

Thermal radiation and fragmentation pathways of photo-excited silicon clusters

“…The other type of radiation pertains to clusters with small heat capacities and/or photons with an energy which is sufficiently large to quench the unimolecular decay completely by emission of a single photon. The modification of the evaporative decay rate for this situation is 50 R n (t) ∝ e −k p, n t t ,…”

“…If, as we suspect, the photons emitted are of an energy so that a single emission quenches the unimolecular decay, the measured (reciprocal) times are simply the Einstein A-coefficients of the excited state times their thermal population. 50 The alternative continuous cooling requires some analysis before the emitted power can be given. Rewriting Eq.…”