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, C162H326 is examined in situ, in real time, by atomic force microscopy. Regions of thickening material can be clearly seen in the height images. The formation of dendritic patterns is observed and holes are often formed at the growth front. These holes do not form after comparable treatment of initially extended chain crystals of the same material. The heating of the extended chain crystals shows a highly mobile phase just before melting. The fact that no holes or dendritic patterns emerge before the melting of the extended chain crystal leads us to attribute this phenomenon to the thickening process. The holes are formed at the growth front as a means of relieving the strain. The formation of thf dendritic structures is also a result of strain: as the strain builds up in the current growth direction, so the growth changes to an alternate crystallographic direction. (C) 2000 Elsevier Science Ltd. All rights reserved.