Featured Research Highlights
“Lighting up” High Response in Thin Film Nanocomposite Sensors
Scientific Achievement Structures of a polymer dimer with photo-activatable triarylsulfonium hexafluoroantimonate and fluroantimonic acid. (hi-res image) Incorporation of ZnO into an epoxy-based photoresist (SU-8) thin polymer film via...
Understanding Motion and Response of Ionic Diblock Copolymer Thin Films for Improved Energy Storage
Scientific Achievement Artistic representation of thin films of charged co-polymers (gray molecules are charged) probed by neutrons (yellow). The neutron data provides a direct measure of nanoscale structural changes under the applied field....
This work shows that nonclassical multiphoton interferences can be achieved at the subwavelength scale in all-dielectric metasurfaces. Simultaneous imaging of multiple projections of quantum states with a single metasurface enables a robust reconstruction of amplitude, phase, coherence, and entanglement of multiphoton polarization-encoded states.
K. Wang, J. G. Titchener, S. S. Kruk, L. Xu, H.-P. Chung, M. Parry, I. I. Kravchenko, Y.-H. Chen, A. S. Solntsev, Y. S. Kivshar, D. N. Neshev, and A. A. Sukhorukov, "Quantum metasurface for multiphoton interference and state reconstruction," Science 361 (6407), 1104-1108 (2018). DOI: 10.1126/science.aat8196
This joint CNMS-CFN research effort built on unique capabilities of two NSRCs and resulted in a new hybrid nanocomposite sensor material with ~20 times higher gravimetric response than pure polymer thin films, and that could be further enhanced by additional 500% under ultraviolet (UV) activation.
E. S. Muckley, L. Collins, A. V. Ievlev, X. Ye, K. Kisslinger, B. G. Sumpter, N. V. Lavrik, C.-Y. Nam, and I. N. Ivanov, "Light-activated hybrid nanocomposite film for water and oxygen sensing," ACS Appl. Mater. Interfaces 10 (37), 31745-31754 (2018). DOI: 10.1021/acsami.8b08072
This work presents a direct observation of electric field induced motion/response of ionic diblockcopolymer thin films with nanoscale resolution using In situ neutron reflectometry measurements and molecular dynamics simulations.
J. W. Dugger, W. Li, M. Chen, T. E. Long, R. J. L. Welbourn, M. W. A. Skoda, J. F. Browning, R. Kumar, and B. S. Lokitz, "Nanoscale resolution of electric-field induced motion in ionic diblock copolymer thin films," ACS Appl. Matter. Interfaces 10 (38), 32678-32687 (2018). DOI: 10.1021/acsami.8b11220
Understanding the 3-D distribution and nature of active sites in heterogeneous catalysts is critical to developing useful structure−function relationships but it is very difficult to achieve such 3-D information. By using the CNMS Atom Probe Tomography (APT) the team was able to reveal the 3-D distribution of elements within a zeolite catalysis, SAPO-34, at different processing stages, including template containing, calcined, and methanol-to-hydrocarbons reacted SAPO-34 with Si as the active site.
J. E. Schmidt, L. Peng, A. L. Paioni, H. L. Ehren, W. Guo, B. Mazumder, D. A. Matthijs de Winter, O. Attila, D. Fu, A. D. Chowdhury, K. Houben, M. Baldus, J. D. Poplawsky, and B. M. Weckhuysen, "Isolating clusters of light elements in molecular sieves with atom probe tomography," J. Am. Chem. Soc. 140, 9154 (2018). DOI: 10.1021/jacs.8b04494
A general approach for quantitatively investigating the spatiotemporal dependence of structural relaxation in deformed polymers based on using small-angle neutron scattering alongside HPC-enabled nonequilibrium molecular dynamics simulations was developed and successfully applied to polymer melts over a wide range of precisely synthesized molecular weights. This work revealed that polymer relaxation at relatively high momentum transfer, Q, and short time can be described by a simple scaling law, with the relaxation rate simply proportional to Q. This is a novel and previously not resolved nor understood behavior and further exemplifies the need to reconsider the theory of polymer flow.
C. N. Lam, W.-S. Xu, W.-R. Chen, Z. Wang, C. B. Stanley, J.-M. Carrillo, D. Uhrig, W. Wang, K. Hong, Y. Liu, L. Porcar, C. Do, G. S. Smith, B. G. Sumpter, and Y. Wang, "Scaling behavior of anisotropy relaxation in deformed polymer," Phys. Rev. Lett. 121, 117801 (2018). DOI: 10.1103/PhysRevLett.121.117801
A unique combination of imaging tools and atomic-level simulations allowed the team to solve a longstanding debate about the properties of a promising material that can harvest energy from light. By using multimodal imaging to “see” nanoscale interactions within a thin film of hybrid organic–inorganic perovskite, CH3NH3PbI3, it was determined that the material is ferroelastic, meaning it can form domains of polarized strain to minimize elastic energy. The work was possible because of the unique environment at CNMS where characterization, theory and synthesis can be integrated to efficiently solve complex nanoscience problems. This alongside strong collaborations with industry allowed CNMS to develop/apply unique tools; in this case an instrument that uses helium ion microscopy (HIM) to remove and ionize molecules was coupled with a secondary ion mass spectroscopy (SIMS) to identify molecules based on their weights and an Interferometric Displacement Sensor (IDS) option for the Cypher AFM (Oxford Instruments Asylum Research) was used for measurements capable of separating cantilever dynamics from displacement of the material due to piezoresponse. Overall, the work demonstrated the ferroic property of twin domains, chemical segregation, and their interplay in CH3NH3PbI3, offering a new exploratory path to improving functional devices.
Y. Liu, L. Collins, R. Proksch, S. Kim, B. R. Watson, B. Doughty, T. R. Calhoun, M. Ahmadi, A. V. Ievlev, S. Jesse, S. T. Retterer, A. Belianinov, K. Xiao, J. Huang, B. G. Sumpter, S. V. Kalinin, B. Hu, and O. S. Ovchinnikova, "Chemical nature of ferroelastic twin domains in CH3NH3PbI3 perovskite," Nature Mater. (2018). DOI: 10.1038/s41563-018-0152-z
A scanning tunneling microscope (STM) tip is used to write and erase (move) individual vacancies on a crystalline lattice in multiple layers of PdSe2, and then to switch the charge state of the defect.
G. D. Nguyen, L. Liang, Q. Zou, M. Fu, A. D. Oyedele, B. G. Sumpter, Z. Liu, Z. Gai, K. Xiao, and A.-P. Li, "3D imaging and manipulation of subsurface selenium vacancies in PdSe2," Phys. Rev. Lett. 121, 086101 (2018). DOI: 10.1103/PhysRevLett.121.086101
Using the ORNL Monochromated Aberration-Corrected Scanning Transmission Electron Microscope (MAC-STEM), Robert Klie, Juan Carlos Idrobo, and co-workers show that electron energy loss spectroscopy (EELS) can distinguish between hydrogen and deuterium vibrational modes. They also observe that encapsulating a small volume of water between boron nitride (BN) monolayers slows down these hydrogen modes.
J. R. Jokisaari, J. A. Hachtel, X. Hu, A. Mukherjee, C. Wang, A. Konecna, T. C. Lovejoy, N. Dellby, J. Aizpurua, O. L. Krivanek, J. C. Idrobo, and R. F. Klie, "Vibrational spectroscopy of water with high spatial resolution," Advanced Materials (2018). DOI: 10.1002/adma.201802702
Scanning probe measurements of ferroelectric switching greatly benefit from machine learning.
J. C. Agar, Y. Cao, B. Naul, S. Pandya, S. van der Walt, A. I. Luo, J. T. Maher, N. Balke, S. Jesse, S. V. Kalinin, R. K. Vasudevan. and L. W. Martin, "Machine detection of enhanced electromechanical energy conversion in PbZr0.2Ti0.8O3 thin films," Advanced Materials (2018). DOI: 10.1002/adma.201800701