Annealing and melting of long-chain alkane single crystals observed by atomic force microscopy

The annealing behaviour of once-folded crystals of the long-chain alkane, C 162H326 is examined in situ, in real time, by atomic force microscopy. Regi ons of thickening material can be clearly seen in the height images. The fo rmation of dendritic patterns is observed and holes are often formed at the growth front. These holes do not form after comparable treatment of initia lly extended chain crystals of the same material. The heating of the extend ed chain crystals shows a highly mobile phase just before melting. The fact that no holes or dendritic patterns emerge before the melting of the exten ded chain crystal leads us to attribute this phenomenon to the thickening p rocess. The holes are formed at the growth front as a means of relieving th e strain. The formation of thf dendritic structures is also a result of str ain: as the strain builds up in the current growth direction, so the growth changes to an alternate crystallographic direction. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.