Temperatures of evaporating clusters

Abstract

The fabrication of new forms of materials through sudden changes in their temperatures is a familiar, if mysterious, process. Thus, it is not known why some substances can be quenched to yield glasses, while others 'prefer' to crystallize. The appearance of quasicrystals in rapidly cooled metallic alloys further illustrates the surprises and challenges that continue to appear. One way to obtain rapid cooling is to isolate a small aggregate of matter: cooling then results as a consequence of the ensuing evaporation. The temperature attained in this process is apt, more than any other parameter, to provide an incisive index to other properties of interest. Here I show that these temperatures, as well as their property of scaling with Lennard-Jones parameters, may often be understood in terms of the 'evaporative ensemble' it is required only that evaporation be occurring.