New research from the Giannis (Yanni) Mpourmpakis and his team introduces the first universal adsorption model that accounts for detailed nanoparticle structural characteristics, metal composition and different adsorbates, making it possible to not only predict adsorption behavior on any metal nanoparticles but screen their stability, as well. The research combines computational chemistry modeling with machine learning to fit a large number of data and accurately predict adsorption trends on nanoparticles that have not previously been seen. By connecting adsorption with the stability of nanoparticles, nanoparticles can now be optimized in terms of their synthetic accessibility and application property behavior. This improvement will significantly accelerate nanomaterials design and avoid trial and error experimentation in the lab. Their work was published in Science Advances on Sept. 13, 2019.
The ability to combine continuously tunable narrow-band terahertz (THz) generation that can access both the far-infrared and mid-infrared regimes with nanometer-scale spatial resolution is highly promising for identifying underlying light-matter interactions and realizing selective control of rotational or vibrational resonances in nanoparticles or molecules. Here, we report selective difference frequency generation with over 100 THz bandwidth via femtosecond optical pulse shaping. The THz emission is generated at nanoscale junctions at the interface of LaAlO3/SrTiO3 (LAO/STO) that is defined by conductive atomic force microscope lithography, with the potential to perform THz spectroscopy on individual nanoparticles or molecules. Numerical simulation of the time-domain signal facilitates the identification of components that contribute to the THz generation. This ultra-wide-bandwidth tunable nanoscale coherent THz source transforms the LAO/STO interface into a promising platform for integrated lab-on-chip optoelectronic devices with various functionalities.
The recently published paper in journal of ACS NANO on Ultrafast Microscopy of Spin-Momentum Locked Surface Plasmon Polaritons is an essential research for designing optical elements to control spin-polarized SPP (surface plasmon polaritons) fields on the nano femto scale. Hrvoje Petek and his colleagues have shown two-photon photoemission electron microscopy images formed by coupling and propagation of longitudinal and transverse components of SPP fields of light. Further, they have also shown the spin-momentum locked SPP wave packets launched with circularly polarized excitation propagate at the same phase and group velocities as for the linearly polarized excitation using time-resolved experiments.
Michael Widom and his colleagues showed what happens at the grain boundaries of one particular alloy of the metals nickel and bismuth that makes it brittle in their paper published in Science. Using advanced electron microscopes, Widom’s collaborators at Lehigh University scrutinized these microscopic grain boundaries at an atomic level. In a "very heroic experimental program" they discovered that when grains met, the bismuth and nickel atoms realigned into lattices to form layered superstructures at the grain boundaries. These superstructures had previously been thought to exist only rarely in some alloys. Finding it at many different boundaries led the team to conclude that these superstructures are probably much more common than many people had thought. 
Owing to high surface to volume ratios and chemical potential, nanoparticles possess unique optical, electrical, and thermal properties, which constitute the basis of novel applications in sensing, catalysis, nanoelectronics, bio-tagging etc. Despite the great advances in the synthesis, the total structure determination of nanoclusters still remains to be a major challenge. Recently Hyung J. Kim and their colleagues have reported the synthesis and crystal structure of a nanocluster composed of 23 silver atoms capped by 8 phosphine and 18 phenylethanethiolate ligands in the journal of Nature Communications.
In the recently published paper in Scientific Reports, Sara A. Majetich and their colleagues have demonstrated the engineering of spin canting across a Magnetic nanoparticles (MNP) via the Dzyaloshinskii-Moriya interaction (DMI). In this paper, they have shown that strong DMI can lead to magnetic frustration within the shell and cause canting of the net particle moment. These results have illuminated how core/shell nanoparticle systems can be engineered for spin canting across the whole of the particle, rather than solely at the surface.
In the recently accepted paper in Physical Review Letter, Hrvoje Petek and his colleagues investigate the coherent electron transfer from an interface state that forms upon chemisorption of Ag nanoclusters onto graphite to a σ symmetry interlayer band of graphite. Interfacial charge transfer is a fundamental process in heterogeneous and plasmonically enhanced catalysis. The charge transfer, however, is thought to be restrained by an interfacial potential barrier, such as a Schottky barrier at a metal-semiconductor interface. With optical excitation, the interfacial charge transfer can also be efficiently completed by coherent dipole coupling between the donor and acceptor bands. In this study Petek and his colleagues advance the time-resolved multidimensional multiphoton photoemission spectroscopy technique to not only pump the donor band and probe the acceptor band, but also directly image the coherent polarization dynamics between them. They discover a direct resonant ... 
James McKone highlighted as an emerging investigator in materials chemistry
From the design of improved batteries to the use of solar and wind power for commodity chemical production, the University of Pittsburgh’s James McKone explores ways that chemical engineering can make the world more sustainable. That’s why his most recent work, investigating ways that the chemical industry can use renewable electricity as its energy source, is featured in the Journal of Materials Chemistry A Emerging Investigators special issue.
The themed issue highlights the rising stars of materials chemistry research, from nanoparticle inks to next-generation solar cells. The featured investigators are early in their careers and were recommended by other experts in the field. “We’re glad to have James on our faculty and know this honor is well-deserved,” says Steven Little, PhD, chair of the Department of Chemical and Petroleum Engineering at the Swanson School. “It confirms what we already know: that his lab’s work has the potential to influence the direction of future discoveries in energy production, energy storage and beyond.”
In his classroom, engineering faculty member Tevis Jacobs is one animated presenter.
The Autumnal Equinox ushers in a season of welcome changes in the Swanson Engineering Department, in the form of faculty promotions! Congratulations to Giannis Mpourmpakis and John Keith for their promotions and to Karl Johnson, Chris Wilmer, and Susan Fullerton for receiving the William Kepler Whiteford Professorship, William Kepler Whiteford Fellowship, and Bicentennial Board of Visitors Faculty Fellowship, respectively.
