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We investigate the kinetics of adsorption of gases on the external surfaces of a carbon nanotube bundle by simulating the elemental processes that take place during equilibration in a kinetic Monte Carlo scheme. By modeling the adsorbing surface as a lattice composed by three or more linear chains of sites characterized by different binding energies, we are able to describe the overall kinetic behavior of the system as well as to identify the processes responsible for the observed behavior. The presence of sites with different binding energies introduces specific paths of adsorption, as particles use the weaker binding sites as temporary intermediate states before being adsorbed on stronger binding sites. This mechanism greatly increases the adsorption rate of the stronger sites with two main consequences as compared with our previous results for homogeneous surfaces: (1) the time evolution of the coverage is nonexponential, and (2) the overall equilibration time as a function of coverage deviates from the linear dependence.

We have studied via in-beam p-ray spectroscopy Po and Po, which are the first neutrondeficient Po isotopes to exhibit a collective low-lying structure. The ratios of yrast state energies and the E2 branching ratios of transitions from non-yrast to yrast states are indicative of a lowlying vibrational structure. The onset of collective motion in these isotopes can be attributed to the opening of the neutron i&3/z orbital at N 112 and the resulting large overlap between the two valence protons in the h9/2 orbital and the valence neutrons in the ii3/q orbital.PACS number(s): 27.80.+w, 21.10.Re, 23.20.En, 23.20.Lv