Ionization potentials, dissociation energies and statistical fragmentation of neutral and positively charged small carbon clusters

Abstract

Dissociation energies, ionization potentials and fragmentation dynamics of neutral, singly-and doubly charged small carbon clusters have been theoretically studied with a combination of the density functional theory, the coupled cluster method and the the statistical model microcanonical Metropolis Monte Carlo. The second ionization potential decreases with the cluster size and is larger than the first one, which also decreases with the size showing oscillations. Dissociation energies also oscillate with the cluster size, being those with an odd number of atoms more stable. C 3 cluster has the largest dissociation energy. The combination of a statistical treatment for the cluster fragmentation with experimental results has allowed us to evaluate the energy distribution in collisions experiments.

Theoretical study of the stability of small triply charged carbon clusters Cn3+ (n=3–12)

“…In particular, ejection of C + is the most favorable process. This is at variance with the results reported for singly- [69] and doubly-charged [35] small carbon clusters, for which evaporation of a neutral trimer has the lowest dissociation energy. This is because C 3 has an unusually high stability [70].…”

Radiative cooling of ${\rm C}_7^-$C7−

“…The contribution from other decay channels can be estimated from comparison of activation energies of the different channels. Electron affinities of small carbon clusters from photo-electron spectroscopy 15 and calculations of dissociation energies of neutral carbon clusters 16 give the dissociation energies of C − 7 for the different neutralization channels. The process C − 7 → C − 4 + C 3 has the lowest calculated dissociation energy with a value of 5.0 eV, considerably higher than the EA of C − 7 of 3.36 eV.…”

Impact of directional walk on atom probe microanalysis

“…Phosphorus being mono-isotopic, this procedure cannot be applied, but as no peak is observed at 31 and 62 Da, it is unlikely that P 2 molecular ions are formed and bias P concentration measurements. These molecular clusters are likely to be post-ionized in the vicinity of the specimen surface [58], making them unstable and likely to dissociate. Interestingly, we did not observe a clear correlation between the different peaks of C (at 6,12,18,24 Da) and the different loci over the surface, which can be explained by the relatively limited differences between the electric field in these regions.…”