Featured Research Highlights
Temperature Measurement by a Nanoscale Electron Probe Using Energy Gain and Loss Spectroscopy
Scientific Achievement A monochromated scanning transmission electron microscope (STEM) directly measures the local temperature at the nanoscale. Significance and Impact Heat flow and dissipation often depend on nanoscale features in a material, yet...
CNMS nanofabrication capabilities were used to create samples that enable cathodoluminescence (CL) observations in a Scanning Transmission Electron Microscope (STEM), illustrating the strong connection between CNMS and the QIS group, and demonstrating key capabilities of interest to the QIS community: Plasmon modes were visualized in e-beam patterned Archimedean nanospirals (J.A. Hachtel et al, Optics Lett., 43, 927 (2018). DOI: 10.1364/OL.43.000927), and strong photon correlations were measured in patterned nanodiamond (M.A. Feldman et al., Phys. Rev. B, 97, 081404(R) (2018). DOI: 10.1103/PhysRevB.97.081404)
Cleaning, milling, and modifying graphene is now possible in a single tool, using Ar ion clusters.
S. Kim, A. V. Ievlev, J. Jakowski, I. V. Vlassiouk, X. Sang, C. Brown, O. Dyck, R. R. Unocic, S. V. Kalinin, A. Belianinov, B. G. Sumpter, S. Jesse, O. S. Ovchinnikova, "Multi-purposed Ar gas cluster ion beam processing for graphene engineering," Carbon 131, 142 (2018). DOI: 10.1016/j.carbon.2018.01.098
The monochromated, aberration-corrected scanning transmission electron microscope (“MAC-STEM”) directly measures the local temperature at the nanoscale, without having to rely on calibration.
J. C. Idrobo, A. R. Lupini, T. Feng, R. R. Unocic, F. S. Walden, D. S. Gardiner, T. C. Lovejoy, N. Dellby, S. T. Pantelides, and O. L. Krivanek, "Temperature measurement by a nanoscale electron probe using energy gain and loss spectroscopy," Phys. Rev. Lett. 120, 095901 (2018). DOI:https://doi.org/10.1103/PhysRevLett.120.095901
Thermoplastic elastomers (TPEs), such as styrenic based automobile tires, are ubiquitous in our society. But styrenic based TPEs suffer from low upper service temperatures and poorer mechanical properties. Here by using a facile synthesis approach, a new class of all-acrylic superelastomers was developed that show superior mechanical strength and higher upper service temperatures.
W. Lu, A. Goodwin, Y. Wang, P. Yin, W. Wang, J. Zhu, T. Wu, X. Lu, B. Hu, K. Hong, N.-G. Kang, and J. Mays, "All-acrylic superelastomers: facile synthesis and exceptional mechanical behavior," Polymer Chemistry 9, 160 (2018). DOI: 10.1039/C7PY01518F
A forty-year-old hypothesis in the classical tube theory for polymer rheology is directly examined by large-scale non-equilibrium molecular dynamics simulations. We show that the characteristic features associated with the chain retraction mechanism are not observed, providing a critical step in improving our understanding of the deformation and flow behavior of polymers.
W.-S. Xu, J.-M.Y. Carrillo, C. N. Lam, B. G. Sumpter, Y. Wang, "Molecular dynamics investigation of a relaxation mechanism of entangled polymers after a large step deformation," ACS Macro Letters 7, 190 (2018). DOI: 10.1021/acsmacrolett.7b00900
Based on ab initio density functional theory, a material composed of graphene with the addition of aluminum was designed to enable a versatile conversion of nitrogen into ammonia without relying on transition metals.
Y.-H. Tian, S. Hu, X. Sheng, Y. Duan, J. Jakowski, B. G. Sumpter, and J. Huang, "Non-transition-metal catalytic system for N2 reduction to NH3: a density functional theory study of Al-doped graphene," J. Phys. Chem. Lett. 9, 570 (2018). DOI: 10.1021/acs.jpclett.7b03094
A simple, wafer-scale process is introduced to rapidly grow graphene layers; multiple techniques at CNMS were used to characterize their structure and quality.
Ivan Vlassiouk, Yijing Stehle, Pushpa Raj Pudasaini, Raymond R. Unocic, Philip D. Rack, Arthur P. Baddorf, Ilia N. Ivanov, Nickolay V. Lavrik, Frederick List, Nitant Gupta, Ksenia Bets, Boris I. Yakobson, and Sergei Smirnov, “Evolutionary Selection Growth of Two-Dimensional Materials on Polycrystalline Substrates," Nature Materials 2018. DOI: 10.1038/s41563-018-0019-3
Z-contrast Scanning Transmission Electron Microscopy performed at CNMS shows the “tunnel” (or “channel”) structure in stable MnO2 nanowires, which have precisely tuned sizes that give them selectivity to particular ions in brackish water.
B. W. Byles, D. A. Cullen, K. L. More, and E. Pomerantseva, "Tunnel structured manganese oxide nanowires as redox active electrodes for hybrid capacitive deionization," Nano Energy 44, 476-488 (2018). DOI: 10.1016/j.nanoen.2017.12.015
Helium ion microscopy is shown to be a highly promising method to quickly determine porosity on commercial SiO2 samples commonly used for catalysis, outperforming SEM by overcoming charging effects (or requirement of sample pretreatment) and providing higher resolution as well as providing much faster and more detailed information than gas absorption methods.
M. J. Burch, A. V. Ievlev, K. Mahady, H. Hysmith, P. D. Rack, A. Belianinov, and O. S. Ovchinnikova, "Helium ion microscopy for imaging and quantifying porosity at the nanoscale," Anal. Chem. 90, 1370-1375 (2018). DOI: 10.1021/acs.analchem.7b04418