Molecular Foundry users from Penn State University and Cornell University have worked with staff to describe the first atomic scale Light-emitting, four-armed nanocrystals could someday form the basis of an early warning system in structural materials by revealing microscopic cracks that portend failure, thanks to recent research by Molecular Foundry staff and users.
The researchers embedded tetrapod-shaped quantum dots, which are nanosized semiconducting particles, in a polymer film. The tetrapods’ cores emit fluorescent light when their arms are twisted or bent out of shape. This indicates the polymer is undergoing a degree of tensile or compressive strain, from which stress over sub-micron-scale regions of the material can be detected. Such stress can cause nanoscale cracks to develop into macroscopic failure. Initial tests show the tetrapods can cycle more than 20 times without losing their ability to sense stress, and they don’t degrade the strength of the polymer in which they’re matrixed.
Electron tomography of the tetrapods under stress was conducted at the Molecular Foundry and atom-scale computer simulations of the tetrapod were conducted at the National Energy Research Scientific Computing Center (NERSC).