Radiative Cooling Of Thermally Excited Electronic States Of Carbon Clusters

Carbon clusters have attracted extensive attention since fullerenes were discovered.At present,there are many basic researches and related applied basic researches in physics,material science,chemistry and other fields on the carbon clusters.On the other side,radiation cooling at the micro level has developed very fast in atomic physics,astrophysics and other fields in recent years as an important reaction channel in unimolecular reactions.What's more,for the carbon macromolecule?fullerene,for example?and carbon clusters with negative charge,there have been a lot researches both in domestic and abroad.However,there are not a lot studies on the field of carbon cationic clusters which are also very important.In this thesis,we produced the carbon cationic clusters?CN+,N=8,10,13-16?by the laser ablation and the original material was graphit.Then we used the electrostatic ion storage ring of Tokyo Metropolitan University to detect the spontaneous decay and photon enhanced decay of our carbon cationic clusters and analyzed the whole process of carbon clusters by the theoretical analysis and experimental data statistics.The main contents and results are listed as following:The carbon clusters were produced by laser ablation on graphit and then they were accelerated and selected for the positive charged ones by an electronic field.And then all the clusters from the source were mass-selected in the storage ring.We analyzed the purity of the cluster source,and also discussed the small peak problem of carbon in the experiment including its influence on the experimental results.After that,we allowed the clusters in the experiment to decay spontaneously in the storage ring and then shot them by the laser with different wavelengths?480nm?2.58 e V?,520nm?2.38 e V?,620nm?2.00 e V?and 625nm?1.98 e V??at different timings?0.2152 ms,0.4335 ms,0.6942 ms,0.7278 ms,0.7444 ms and 0.8511ms?.Besides,the experiment was analyzed and discussed theoretically through vibration frequency,level density and so on.And it was firstly found that the small peak problem wouldn't have any influence on the experiment's result.What's more,for carbon clusters CN+?N=13-16?,the decay had a very similar decay trend before and after laser-shooting.And there was indeed another decay channel which would suppress the original decay of carbon clusters by an exponential law in the experiments.There was also a phenomenon of recurrent fluorescence during the process.That means we detected the radiative cooling throughour experiments.We also analyzed the whole process in theory.Finally,the cooling rates of the six carbon cationic clusters were obtained through experiments which had a maximum value at N=8 of 2.6×104s^-1 and a minimum at N=13 of 4.4×103s^-1.