Stm

Another installment in the annals of the bullying of the Shockley surface state, this time the trick isn’t exotic adatoms or massive molecular weight, just a 120° tilt of hexaazatriphenylene (HAT) ligands that converts an achiral lattice into a pair of enantiomeric 2-D metal–organic frameworks. The result: chirality-imposed scattering potentials that lift degeneracies and open ΔE ≈ 80 meV gaps in the Ag(111) two-dimensional electron gas while leaving the global periodicity intact. ...

Jules has put in the hard yards implementing nanonisTCP as a python module, and leveraged that to create scanbot, a tool for automating the tasks of preparing a good imaging & spectroscopy probe, as well as a suite of functions for performing nuanced, drift-corrected measurements over very long timescales. See the below example of systematically grid scanning 100x100nm images to concatenate a comprehensive view of the surface. Right is the upper left red corner, where self-assembled molecular islands are visible. ...

We had the opportunity to use the new toroidal analyzer at the Australian synchrotron to do ARPES of self-assembled monolayers of MgPc on Ag100. Careful simultaneous fitting of different high-symmetry EDC measurements, in concert with the structural understanding gleaned from ncAFM & LEED characterization, allowed us to tease out a feature with bandwidth 20 meV, which was surprising to us given that we did the ARPES at room temperature. ...

9-azidophenanthrene produces a rich manifold of products when deposited on Ag(111). The images we took for this study inspired this work to develop a lightweight script to count the molecules we observed, and categorize them. Our personal journey of computer vision rediscovery led us to Zernike moments, a rotationally invariant basis set that solves the problem of identifying the same molecules with relative rotations, in an image. We put some effort into making this module user-friendly, the example scripts offer a reasonable template to apply to any old SXM file you might want to histogram. ...

nc-AFM atomic registration of single MgPc molecule on Ag100 (surface atoms top and bottom stripes) Marina Castelli studied the phthalocyanine containing magnesium (MgPc) via 5K scanned probe microscopies extensively during her PhD. ‘Routine’ STM characterisation showed that the molecules were interacting with one another on the Ag100 surface. ncAFM showed identical contrast for all molecules, pointing to an electronic origin to the observed changes in appearance. Our key observation was to track the shape of the occupied LUMO for different pairwise distances, an electronic feature that otherwise remained isoenergetic. ...