TEM team & collaborators from left to right: Dayne Swearer, Rowan Leary, Emilie Ringe, and Sadegh Yazdi.

Lab focus

The Ringe Group was established in 2014 in the department of Materials Science and NanoEngineering (MSNE) at Rice University, Houston...

 

Lab focus

The Ringe Group was established in 2014 in the department of Materials Science and NanoEngineering (MSNE) at Rice University, Houston, TX, USA. Emilie Ringe and her...

Lab focus

The Ringe Group was established in 2014 in the department of Materials Science and NanoEngineering (MSNE) at Rice University, Houston, TX, USA. Emilie Ringe and her group focus on understanding and controlling light-matter interactions in small metallic nanoparticles for applications in biological sensing, enhanced spectroscopy, and light-driven heterogeneous catalysis.

By using correlated optical spectroscopy and electron microscopy tools, the group studies a phenomenon called localized surface plasmon resonance (LSPR), a type of light-matter interaction. LSPRs are a collective oscillation of the conduction electrons in a metal particle that leads to bright colors as well as strong electric fields at the surface of the particle. The resonance frequency changes with the surrounding environment, such that LSPR have exciting applications as nanosensors. Moreover, the strong fields can boost the catalytic activity of the metal surfaces.

Both electrons and photons can interact with plasmon resonances, yielding either photons or electrons. Using electron energy loss spectroscopy (EELS) and cathodoluminescence (CL), techniques using an electron-based excitation and yielding an electron and a photon signal, respectively, the Ringe group studies the symmetry and localization of plasmon modes. Recently, work on Au/Pd nanoparticles has demonstrated that these alloy nanoparticles containing a poor plasmonic metal (Pd in this case) can nevertheless sustain a strong plasmonic response, enabling applications such as plasmon-enhanced photocatalysis and in-situ reaction monitoring and switching. Multiple size-dependent LSPRs and strong spatially localized fields at the Pd-rich tip of stellated particles were observed, where the composition is in fact least favorable for plasmon resonances. A strong substrate coupling was demonstrated via EELS tilt series and shows that Pd is fully participating in the resonances observed. Results are shown below.

 

 

 

 

 

 

 

 

Please visit the lab's website for more information.

Publications

E. Ringe, C.J. DeSantis, S.M. Collins, M. Duchamp, R.E. Dunin-Borkowski, S.E. Skrabalak, P.A. Midgley. "Resonances of nanoparticles with poor plasmonic metal tips" Scientific Reports 5. 2015, 17431, doi:10.1038/srep17431.

Lab focus

The team at Electron Microscopy Group in Nano-Materials Research Institute of AIST aims to realize the characterization of nano-materials at a single atomic level by using the high performance electron microscopy. They have developed the low-accelerating voltage transmission electron microscopy (TEM) and scanning TEM (STEM) equipped with high-order aberration correctors to visualize the atomic structures of low-dimensional materials such as carbon nanotubes, graphene and transition-metal dichalcogenides as well as soft matters such as organic molecules and bio-materials. They have also focused on the chemical assignment of single atoms or molecules correlated to the atomic structures including defects and dopants by means of electron energy-loss spectroscopy (EELS).

Publication highlights

The lab has reported the ionic atomic chain in which two chemical elements line up alternately (Fig.1), showing distinct physical properties from the bulk structures1,2. Connected to this work, they have also demonstrated the single atom identification of light elements including Lithium (Fig. 2) which is the lightest element ever identified as a single atom by using EELS combined a STEM2.

Figure 1. STEM EELS characterization for a CsCl atomic chain inside a double-walled carbon nanotube (DWNT). The Cs and Cl atoms are lined up alternatively as shown in the left model. Since Cl is much lighter than Cs, the ADF image only shows the Cs atomic positions as brighter spots and the Cl atoms are hardly visible. However this, the EELS map for the Cl L-edge (purple spots in the left panel) clearly shows the existence of Cl atoms in between Cs atoms2. EELS data are recorded by a GIF Quantum® spectrometer designed for the low-voltage TEM.

Figure 2. STEM-EELS characterization for a LiI atomic chain inside double-walled carbon nanotube (DWNT). The LiI atomic chain exists as a double lined chain inside the DWNT as shown in the left model. While the ADF image only shows the I atomic positions, the EELS chemical map for the Li K-edge shows the Li atomic position as a zigzag pattern between I atoms2. EELS data are recorded by a GIF Quantum spectrometer designed for the low-voltage TEM.

Electron Microscopy group is in Nano-Materials Research Institute of AIST, Japan. Please visit the lab's website for more information.

References

  1. R. Senga, H.-P. Komsa, Z. Liu, K. Hirose-Takai, A. V. Krasheninnikov and K. Suenaga Nature Mat. 2014, 13 (11), 1050–1054.
  2. R. Senga and K. Suenaga, Nature Commun. 2015, 6, 7943.

Additional Publications

Y.-C. Lin, P. -Y. Teng, P. -W. C, K. Suenaga. "Exploring the Single Atom Spin State by Electron Spectroscopy" Phys. Rev. Lett. 2015, 115, 206803.