学术报告
题目：Characterizing Localized Surface Plasmons using Electron Energy-Loss Spectroscopy
报告人：李国梁博士（Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States）
时间：2016年3月9日(星期三)下午15:00-16:00
地点：yl23455永利官网南校区双超所211报告室
简历：
李国梁博士，于2005考入yl23455永利官网物理教学改革试验班，主修材料科学与工程并辅修应用物理，于2009年毕业获得学士学位；同年进入美国田纳西大学材料科学与工程系攻读博士并于2013年获得博士学位；2013-2014转入田纳西大学化学系从事博士后研究；2014至今在美国圣母大学化学与生物化学系从事博士后研究；在美期间长年保持与橡树岭国家实验室扫描透射电镜组的密切合作。主要研究:扫描透射电镜显微学（Scanning Transmission Electron Microscopy）,电子能量损失谱学（Electron Energy-loss Spectroscopy），表面等离子体光子学（Plasmonics），半导体薄膜材料界面分析（Interfaces in Thin-Film Semiconductor Materials）。在Annual Review of Physical Chemistry, Nano Letters, ACS Nano, JPC Letters等刊物发表论文8篇。
Abstract:Localized surface plasmon resonances (LSPRs) are the coherent and collective oscillations of conduction band electrons at the surface of metallic nanoparticles. LSPRs are known to localize far-field light to a sub-diffraction-limited length scale, yielding an intense electric field at the particle surface. This effect has been harnessed to dramatically enhance light-matter interactions, leading to a variety of applications such as surface-enhanced Raman spectroscopy (SERS),1photothermal cancer therapy2and solar energy harvesting.3Though a variety of near- and far-field optical methods are used to probe LSPRs, the spatial resolution of these methods is on the order of tens of nanometers,4limiting their effectiveness. In contrast, electron energy loss spectroscopy (EELS) performed in a scanning transmission electron microscope (STEM)combines sub-nanometer resolving power with the capability to excite both optical-accessible and –inaccessible plasmon modes and thereforehas emerged as one of the leading techniques used in characterizing LSPRs.In this presentation, I will first briefly introduce (1) the basics of LSPRs and (2) the STEM/EELS technique and then demonstrate (3) the power of STEM/EELS in the characterization of LSPRs based upon my previous work. Finally I will (4) highlight recent research interests of the plasmonics community and what possibilities I pursue to make impact. Figure 1 is a schematic of the working principle of STEM/EELS. Figure 2 shows selected STEM/EELS results.
Figure 1.Schematic of the working principle of STEM/EELS
Figure 2.STEM/EELS results demonstration. (a) Mapping plasmon modes of Au nanoparism (150 nm in edge length). (b) Imaging plasmon bonding of a Ag nanoparticle dimer (165 nm in diameter).
References
(1). Nie, S.; Emory, S. R. Science 1997, 275, (5303), 1102-1106.
(2). Morton, J.; Day, E.; Halas, N.; West, J., Nanoshells for Photothermal Cancer Therapy. In Cancer Nanotechnology, Grobmyer, S. R.; Moudgil, B. M., Eds. Humana Press: 2010; Vol. 624, pp 101-117.
(3). Clavero, C. Nature Photonics 2014, 8, (2), 95-103.
(4). Ringe, E.; Sharma, B.; Henry, A.-I.; Marks, L. D.; Van Duyne, R. P. Physical Chemistry Chemical Physics 2013, 15, (12), 4110-4129.
