Strain induced dewetting of a molecular system: bimodal growth of PTCDA on NaCl.
Submonolayer coverages of the molecule 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) deposited on NaCl(001) surfaces were imaged with high resolution noncontact-atomic force microscopy. Two island types were observed: monolayer islands with a p3x3 epitaxy at low coverage and a mixture of these and bulklike crystallites at higher coverage. The transition between the pure monolayer islands and mixed islands occurs at approximately 0.85 ML, corresponding to a complete p3x3 layer. Calculations show the p3x3 epitaxy to be incompatible with a multilayer crystal of PTCDA. Consequently, the growth of additional layers results in an adaptation of the interface structure forcing a dewetting transition.
Centre for the Physics of Materials and Department of Physics, McGill University, Montreal, Quebec, Canada H3A 2T8.
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Burke
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Ji
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Mativetsky
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Topple
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Fostner
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Gao
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Guo
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Grütter