MRI: Acquisition of an Electron Energy-Loss Spectrometer for In Situ Time-Resolved Chemical Mapping of Nanomaterials

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This award is supported by the Major Research Instrumentation and the Chemistry Research Instrumentation programs. Professor Renske van der Veen from University of Illinois Urbana-Champaign and colleagues Jian-Min Zuo, Prashant K Jain, Qian Chen and Pinshane Huang have acquired an electron energy-loss spectrometer (EELS) to be added to a dynamic environmental transmission electron microscope (DETEM). An electron energy loss spectrometer measures the changes in energy distribution of an electron beam of known energy that is transmitted through a thin sample being analyzed. Each interaction between the electron beam and the sample produces a change in energy that is characteristic of the material since energy is lost. This is resembles a ball bouncing on a surface such as a basketball court. With each bounce, a bit of energy from the ball is transferred to the surface and consecutive bounces are shorter and shorter. This loss of energy is referred to as an inelastic event. This type of measurements allow the researchers to investigate the elemental components of a material. With some care, and looking at a broad range of energy loss, the researchers determine the types of atoms, number of atoms of each type, being hit by the electron beam. Because this spectrometer is installed on a dynamic environmental transmission electron microscope, additional information is obtained that can map where various components are in a given sample. In essence this is a chemiscope capable of capturing element-specific snapshots of evolving nanostructures and soft materials undergoing temperature-, gas-, voltage-, or light-induced chemical transformations on very short time scales ranging from femtoseconds-milliseconds. These capabilities enable discoveries in heterogeneous catalysis, polymer physics, electrochemical charge transport, biofunctional interfaces, and ultrafast materials switching, which are critical for example in clean energy generation, biomedical imaging, flexible electronics, and information storage. Moreover, the tool is a vital regional and national resource for in situ chemical mapping. Large demand for these capabilities are met by housing the EELS system at the UIUC Materials Research Laboratory (MRL), a nationally recognized user facility, where it provides opportunities for research and for training the next generation of scientists and engineers in cutting-edge environmental electron microscopy. The spectrometer is used in various courses and in outreach through a workshop and a program reaching to high school girls.The proposal is aimed at enhancing research and education at all levels. The spectrometer especially impacts studies of field-induced formation and restructuring of nanoparticle surfaces and interfaces. The instrument is also used for imaging of soft materials and soft-hard interfaces under dose-controlled conditions and for investigations of ionic diffusion and electrode/electrolyte interactions. In addition, it is employed to control matter far from equilibrium such as that in photoinduced phase transitions and ultrafast exciton dynamics in photoactive materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.