Shell-effects in heavy alkali-metal nanowires
  We supplement our previous observations of the shell effect in alkali-metal nanowires (Li, Na, K) with data extended to the heavy alkalis Rb and Cs. Our observations include: i) a non-monotonous dependence of conductance-histogram peak heights on atomic weight, ii) a rapid transition to an atomic shell structure at elevated temperatures, and iii) a ''reverse'' atomic-electronic shell transition, caused by the closeness to the liquid state. 
A. I. Yanson, I. K. Yanson, J. M. van Ruitenbeek