Local strain in the Au(111) surface revealed by a supramolecular overlayer

Surface strain plays a critical role in determining the physical properties and reactivity of crystalline materials. Identifying its nanoscale distribution remains a major challenge because most conventional methods average over larger areas of surfaces. Here, we present a method that employs a supramolecular overlayer as a local strain sensor. A co-assembled supramolecular overlayer of linear and triangular molecules show a hexagonal pattern on the Au(111) substrate in scanning tunneling microscopy. Linear molecules exhibit unequal orientation probabilities among three possible directions, which correlate directly with the local strain environment. Single-molecule manipulation experiments confirmed these orientational preferences. This study highlights supramolecular overlayers as facile molecular sensors for mapping nanoscale surface strain, offering new opportunities for probing strain-related phenomena in surface science and nanotechnology.