Vaporization of solids: evidence for a zipper mechanism in the retarded vaporization of arsenic

Recent observations indicate that the rate of evaporation of elemental arsenic into a vacuum is determined by the rate of formation, at screw dislocations, of kinks in ledges of molecular height. Once formed, a kink advances along the ledge, which makes a continuous spiral ramp outward from the dislocation, until the ledge terminates. A kink advances by releasing As(4) molecules from the ledge. A given kink releases almost 10(6) As(4) molecules before the next kink is initiated.