Homogeneous nucleation of carbon dioxide in supersonic nozzles II: molecular dynamics simulations and properties of nucleating clusters

Abstract

Large scale molecular dynamics simulations of the homogeneous nucleation of carbon dioxide in an argon atmosphere were carried out at temperatures between 75 and 105 K. Extensive analyses of the...

Shells in CO2 clusters

“…The value is close to the one found theoretically in Ref. 23 where macroscopic parameters given by the brown field. Note the large difference between the scales of the variation of the stability functions and the dissociation energies.…”

“…The good agreement between stability functions extracted from mass spectra produced under a range of different conditions allows us to conclude that they reflect inherent cluster properties, consistent with the hypothesis that they are shaped by evaporative events after production. In contrast, the envelope functions differ widely for different source conditions, as expected from the correspondingly different nucleation parameters [15,23]. Indeed, although it cannot be excluded that clusters may undergo some additional collisions even in the postskimmer collimated flow, strong size-to-size intensity oscillations are a hallmark outcome of evaporative processes.…”

“…In contrast, the envelope functions differ widely for different source conditions, as expected from the correspondingly different nucleation parameters. 15,23 Indeed, although it cannot be excluded that clusters may undergo some additional collisions even in the post-skimmer collimated flow, strong size-tosize intensity oscillations are a hallmark outcome of evaporative processes.…”

“…The value is close to the one found theoretically in ref. 23 where macroscopic parameters were used to adjust the interaction potentials and simulations were performed for finite excitation energy clusters in similar size ranges.…”

New Particle Formation from the Vapor Phase: From Barrier-Controlled Nucleation to the Collisional Limit

“…Additional errors may arise from insufficiently accounting for thermal contributions from all existing cluster configurations and the assumption that all vibrations are (quasi-)harmonic and uncoupled, which might not be completely valid, as the small CO 2 clusters may behave in a liquid-like manner at the studied temperatures. 35 Given the complexity of nucleation processes and the very high sensitivity of nucleation rates to system parameters, such good agreement is extremely encouraging. This is especially true in light of the 1 order of magnitude uncertainties in the absolute values of the experimental rates and the fact that the theoretical predictions are essentially free of adjustable parameters and made independently of the experimental results.…”