Kinetics of radiation cooling of fullerenes

10.1007/s11455-008-3013-3

“…High thermal mobility of molecules in a cluster leads to oscillations of the dipole moment of water clusters, thus making them optically active in the IR spectral range. Our experiments with cluster beams [15] showed that coarse clusters of water are subject to evaporation on the passage through a channel with heated walls. In view of this phenomenon, a question naturally arises as to what can be the ecological consequences of cluster ejection into the Earth's atmosphere by jet engines of airplanes.…”

Direct experimental evidence for the thermal nature of delayed electron emission from a superhot C60 molecule

“…Delayed ionization of C 60 induced by electron impact was reported before ͑but with appearance energy larger by 10 eV then measured here͒ and suggested to originate from high Rydberg states 3 or some superexcited autoionizing states. 6 Even if the electron impact excitation in our experiment can access such long-lived electronic states, these excitations should live longer than t 1 ͑45 s͒, be insensitive to electric fields of ϳ100 V/cm ͑at EA1͒ and at the same time be very effectively coupled to ͑and pump energy from͒ nuclear motions. Multiple-triplet excitation in superhot C 60 should decay to the singletic vibrational manifold within nanoseconds.…”

“…The most notable example for this rather general phenomena is the C 60 molecule which became a model specie for studies of delayed electron emission. [1][2][3][4][5][6] The basic question underlying the on-going debate 5,7-9 is whether the observed delayed ionization phenomena is truly thermal in nature ͑thermionic emission͒ or related with excitation of long lived metastable electronic states like multipletriplet excitations, 5,8 high Rydberg states, 3 or some slowly decaying autoionizing states. 6 The controversy is rooted in the fact that for all experiments performed so far ͑mainly UV multiphoton adsorption͒ energy was pumped into the C 60 molecule nonthermally thus enabling direct access to electronic excitations and resulting in a generally ill-defined internal energy distribution.…”

“…Under this assumption one can write: N(E e )ϰ͓ f Ϫ pi (E e )͔/ f . As absolute values of pi (E e ) for C 60 were already reported for a few values of E e ͓together with relative pi (E e ) cross sections͔, 6,18,19 we will express N(E e ) in the form:…”

“…The contribution of C 2n ϩ2 is negligible. The measured values 6,18,19 of pi (E e ) were converted to pi ͑30 eV͒ ͑where one can neglect fragmentation of C 60 ͒ using the reported ionization efficiency curves, 6,18,19 and an average value of pi (30 eV)ϭ30 Å 2 was obtained. The f value was taken as R h 2 with R h ϭ5 Å ͑van der Walls radius͒.…”