Frontiers in Chemical Imaging
Guest Speakers
2015
Dr. Wah Chiu
Alvin Romansky Professor of Biochemistry
Baylor College of Medicine
“Cryo-Electron Microscopy and Tomography of Molecular Machines and Cells"
Monday, January 19, 2015
EMSL Auditorium – 11:00 AM
2014
Dr. Diane S. Lidke
Department of Pathology
Cancer Research Facility
"Single-Molecule Imaging of Protein Dynamics on Live Cells"
Friday, May 30, 2014
BSF Darwin Room – 11:00 AM
Pinshane Huang
School of Applied and Engineering Physics
Cornell University
"Transmission Electron Microscopy of 2D Materials: A Platform for Understanding Materials Down to the Single Atom Scales"
Friday, April 11, 2014
EMSL Auditorium – 11:00 AM
2013
Dr. Jinghua Guo
Advanced Light Source Division
Lawrence Berkeley National Laboratory
"Probing the Emerging Mesoscale Phenomena of Energy Materials from In-Situ Soft X-ray Spectroscopy"
Wednesday, December 11, 2013
EMSL Boardroom – 10:00AM
Dr. Manfred Auer
Life Sciences Division
Structural Biology and Imaging
Lawrence Berkeley National Laboratory
"Imaging Microbial Communities Across the Scales: from Macromolecular and Cellular Strategies to 3D Community Organization"
Monday, November 4, 2013
BSF Darwin – 9:30 AM
Dr. Kenneth Kemner
Environmental Research Division
Argonne National Laboratory
"Chemical Imaging of Complex Systems with Synchrotron X-ray Radiation"
Wednesday, January 16, 2013
EMSL Auditorium – 10:30 AM
Dr. Frances M. Ross
Manager, Nanoscale Materials Analysis Department
IBM T. J. Watson Research Center
"Visualizing Crystal Growth in the Transmission Electron Microscope"
Tuesday, November 19, 2013
EMSL Auditorium - 10:00 AM
In situ transmission electron microscopy is a unique and exciting technique for visualizing and quantifying crystal growth. Physical and chemical vapor deposition and even electrochemical deposition can be carried out inside the microscope. By recording movies while growth takes place, we can measure kinetics, identify transient structures, and determine mechanisms. Here we describe two materials systems that illustrate the opportunities and challenges of in situ microscopy: the vapor-phase self-assembly of semiconductor nanowires from catalytic particles, and the liquid-phase electrochemical deposition of metals to form nuclei, thin films and dendrites. The range of materials and processes that can be examined suggest that in situ microscopy of crystal growth can play a key role in basic physics understanding and nanomaterials design.
Dr. Pupa Gilbert
Dr. Pupa Gilbert
Professor, Department of Physics
University of Wisconsin-Madison
"Biominerals and Their Formation Mechanisms"
Tuesday, July 30, 2013
EMSL Auditorium - 9:00 AM
Carbonate biominerals are among the most interesting materials on Earth. They play a major role in the CO2 cycle, buffer acidifying oceans, and master templation, self-assembly, nanofabrication, phase transitions, space filling, crystal nucleation and growth mechanisms. An imaging modality, introduced in the last 6 years, enables direct observation of the orientation of carbonate crystals, at the nano- and micro-scale, and the interesting patterns they form. This is Polarization-dependent Imaging Contrast (PIC) mapping, which is based on X-ray linear dichroism, and uses PhotoElectron Emission spectroMicroscopy. I will discuss PIC-mapping results from biominerals, including mollusk shells, sea urchin teeth, and ascidian spicules, and show that these led to fundamental discoveries on the formation mechanisms of biominerals.
2012
Xiaoqing Pan, Ph.D.
Xiaoqing Pan, Ph.D.
Department of Materials Science and Engineering
University of Michigan
"Probing the Structure and Dynamic Behaviors of Nanostructured Materials by in situ TEM"
Friday, November 16, 2012
EMSL 1077 - 10:00AM
As advances in aberration-corrected transmission electron microscopy (TEM) have enabled the determination of the three-dimensional structure of nanostructures and defects with the sub-angstrom resolution, the recent development of in situ holders and environmental cells for TEM allows us to study the dynamic behaviors of materials under applied fields and environments while the atomic structure is imaged directly. In this talk I will show our atomic resolution TEM studies of precious-metal-doped perovskites promoted by researchers in Japan as "intelligent" three-way catalysts (TWCs) for automotive exhaust treatment, using a novel gas-cell specimen holder within an aberration-corrected scanning transmission electron microscope. We found that the precious metals do not cycle between free surfaces and the bulk of the perovskite hosts due to limited ionic diffusion. Our observations show that nanometer-scale metal particles tend to precipitate throughout the bulk of the perovskite upon reduction, and most of the metal that participates in the reversible process of metal precipitation/dissolution remain entirely within the perovskite matrix, where it is unavailable for gas-phase catalysis. I will also show that the atomic scale polarization map in ferroelectrics can be determined using aberration-corrected TEM images owing to the large atomic displacements responsible for the dipole moment. This study reveals how interfaces in complex multidomain geometries lead to the formation of polarization vortices with electric flux closure domains. Using aberration-corrected transmission electron microscopy (TEM) in combination with a customized in situ scanning probing holder the kinetics and dynamics of ferroelectric switching is followed at millisecond temporal and sub-angstrom spatial resolution in an epitaxial bilayer of an antiferromagnetic ferroelectric (BiFeO3) on a ferromagnetic electrode (La0.7Sr0.3MnO3). We observe localized nucleation events at the electrode interface, domain wall pinning on point defects, and the formation of metastable ferroelectric states localized to the ferroelectric and ferromagnetic interface. These studies show how defects and interfaces impede full ferroelectric switching of a thin film. Using the similar techniques the dynamics of ferroelectric switching in a PbZr0.2Ti0.8O3 (PZT) film, which is a key material for nonvolatile ferroelectric memories, was also studied. It was found that 180" polarization switching initially forms domain walls along unstable planes due to the inhomogenous electric field from the small switching electrode. After removal of the external field, they tend to relax to low energy orientations. In sufficiently small domains this process results in complete backswitching. These findings suggest that even thermodynamically favored domain orientations are still subject to retention loss, which must be mitigated by overcoming a critical domain size.
John A. Panitz, CEO
John A. Panitz, CEO
High-Field Consultants, Inc.
"On the trail of the Chimera
The Atom-Probe at the Biological Frontier
Friday, November 09, 2012
EMSL 1077 - 10:00AM
The Atom-Probe may be the ultimate microanalytical tool because a single atomic or molecular species can be identified, imaged and mapped in three dimensions with atomic resolution in most materials [1]. The lure of identifying, imaging and mapping the constituent elements of a biological molecule in the atom probe has been an ongoing quest since its introduction [2-3]. This talk will focus on that quest and in the process describe why the Chimera is still elusive.
- Thomas F. Kelly and David J. Larson. Ann Rev. Materials Res 42 (2012) 1.
- Erwin W. Müller and John Panitz. Proceedings of the 14th International Field Emission Symposium. The National Bureau of Standards, Gaithersburg, MD (1967) 31.
- Erwin W. Müller, John A. Panitz and S. Brooks McLane. Rev. Sci. Instrum. 39 (1968) 83.
Jack D. Griffith, Ph.D.
Jack D. Griffith, Ph.D.
Kenan Distinguished Professor of Microbiology and Immunology and Biochemistry
University of North Carolina School of Medicine
"Electron microscopic visualization of
telomeres, DNA repair factors, and nanoparticles bound to cells"
Tuesday, October 23, 2012
EMSL Auditorium - 9:00AM
High-resolution electron microscopy provides a unique window into the architecture of DNA and DNA-protein complexes. In our studies of the ends of chromosomes (telomeres), we have shown that human chromosomes end in giant duplex loops. The telomeric factors and DNA repair factors involved will be described and EM and biochemical studies used to illustrate how these factors are central to both cancer and aging. A new approach using cryo methods combined with freeze drying and high-resolution metal coating is providing an exciting means to visualize cell structures including actin networks and nanoparticles being taken up by cells. The method and applications will be discussed.
Anthony (Tony) van Buuren, Ph.D.
Nanoscale Integration Science & Technology Group Leader
Physics and Life Sciences Directorate
Lawrence Livermore National Laboratory
"Designer Nanoporous Materials for Energy Storage and Energy Conversion"
Thursday, August 30, 2012
EMSL Auditorium - 9:00AM
Securing this nation's energy future will require developing new materials for energy storage as well as energy conversion. Here, nanostructured - specifically nanoporous - solids could lead to many technological breakthroughs. Their high surface area, electrical conductivity, environmental compatibility and chemical inertness make them promising materials for use as electrode materials in supercapacitors and rechargeable batteries. Understanding how the pore structure and materials' strength evolve as the surface environment is manipulated is a common theme in designing porous materials for these two diverse applications. Measuring changes in morphology and chemistry of the nanoporous materials in situ with small-angle x-ray scattering (SAXS), tomography, and diffractive x-ray imaging has provided the needed feedback to develop nanoporous materials with optimized microstructures for these applications. In many cases, unique properties are observed in nanoporous materials as the surface environment and density are manipulated. Van Buuren will present examples of how SAXS measurements have led to the development of carbon aerogels able to wick cryogenic hydrogen needed for laser fusion targets and development of super strong carbon aerogels able to withstand volume changes associated charge-discharge in super capacitors and rechargeable batteries.
Ian M. Robertson, Ph.D.
Ian M. Robertson, Ph.D.
University of Illinois at Urbana - Champaign
Division Director, Division of Materials Research
National Science Foundation
"Combining in situ TEM Techniques with Three-Dimensional Analysis—a New Approach to Probe Defect Evolution"
Friday, August 10, 2012
EMSL Auditorium - 9:00AM
Two distinct limitations of electron microscopy are that the information is inherently two-dimensional, reflecting information as it is projected on the electron exit surface, and it is a snapshot in the evolution process. One consequence of the latter limitation is that a posteriori analysis is employed to envision how the structure evolved. Both limitations can now be overcome. The former through electron tomography, which enables recovery of the spatial information lost in the beam direction, and the latter through performing dynamic experiments actually in the electron microscope so that the evolution processes are observed directly. Of course electron tomography is again a snapshot in time of the microstructure and the dynamic experiments provide two-dimensional information. A future challenge will be to combine electron tomography with dynamic experimental capabilities such that periodic three-dimensional snapshots of the evolving microstructure will be acquired to enhance the analysis.
The new capability of electron tomography as applied to defect structures will be introduced and it will be demonstrated how this technique when combined with in situ studies as well as with traditional analysis tools is providing insight to defect structures as well as to the interpretation of microstructure evolution. In this presentation specific attention will be given to dislocation interactions with irradiation produced defects as well as with interfaces. Progress towards combining three-dimensional imaging with time resolved experiments will be described.
Kannan M. Krishnan, Ph.D.
Kannan M. Krishnan, Ph.D.
Departments of Materials Science and Physics
University of Washington
"Magnetism and Microstructure: Challenges and Opportunities for Electron Microscopy"
Wednesday, August 8, 2012
EMSL Auditorium - 9:00AM
There has been a renaissance in magnetism and magnetic materials research on the nanometer length scale, driven by discovery of new phenomena, advanced characterization and fabrication capabilities, their demonstrated impact in information storage as well as opportunities in spintronics, energy-conversion and biomedical technologies. Size-dependent scaling laws, exchange, proximity and interface effects, and studies of spin transport are increasingly of fundamental and technological interest. Over the past two decades, my research group has pioneered work in magnetic materials, broadly, in three areas.
- In biomedical nanomagnetics we have been developing multifunction platforms for therapy, diagnostics and imaging based on functionalized, biocompatible, theranostic magnetic nanoprobes. Central to this work are innovations in chemical synthesis of nanoparticles, their size-dependent magnetic properties and specifically tailoring their relaxation dynamics, both Néel and Brownian, to specific applied frequencies.
- We have also extensively studied ultrathin magnetic heterostructures that show a richness in magnetic behavior driven, in part, by exchange, interface, proximity, size and dimensionality effects. Specifically, we work on exchange-bias and exchange-spring behavior in epitaxial thin films and patterned elements.
- Finally, we have worked on understanding the origin of ferromagnetism in doped transition-metal oxides and identified a new class of such materials, dilute magnetic dielectrics.
In light of the recent developments at PNNL, following a summary of our work in this wide range of magnetic materials and plans for the future, this talk will explore some of the key unresolved questions, of both fundamental and technological interest, that may provide opportunities for future collaborative research in chemical imaging and electron microscopy.
Ondrej Krivanek, Ph.D.
Ondrej Krivanek, Ph.D.
President, Nion
"Analyzing Matter Atom-by-Atom with the
Scanning Transmission Electron Microscope"
Wednesday, May 30, 2012
EMSL Room 1077 - 9:00AM
Analyzing matter atom-by-atom with an Å-sized yet intense beam of electrons in a scanning transmission electron microscope (STEM) is now possible, principally because of 5 developments, several of which have been pioneered by Nion. Correction of electron-optical aberrations has resulted in electron beams that are smaller than the typical atom, which means that the beam can be focused on one atom at a time. Aberration correction has allowed this performance to be maintained at low beam energies (30-80 keV), which do not cause knock-on radiation damage in materials such as graphene. As a result, very large electron doses can be used, leading to relatively noise-free images and spectra from individual atoms. Improved cold field emission guns (CFEGs) are allowing electron currents of the order of 0.2 - 1 nA to be packed into the Å-sized probe. Ultra-high vacuum (UHV, pressure < 1x10-9 torr) has become available in the sample chamber, allowing samples to be examined without contamination and without contamination-caused beam-assisted chemical etching. Samples such as graphene have become readily available, allowing atoms to be imaged in non-overlapping configurations, rather than imaging whole columns of atoms, as was the case with thicker samples. These advances will be reviewed and illustrated by practical examples, such as annular dark field (ADF) imaging that identifies all individual atoms in a sample, and electron energy loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDXS) that record spectra from individual foreign atoms in and on graphene. The EEL spectra will be shown to contain fine structures that provide information about the local environment of individual atoms. Our progress on a new instrumentation project - reaching 30 meV and smaller energy EELS resolution with a nm-sized electron probe- will also be described.
Stephen Pennycook, Ph.D.
Stephen Pennycook, Ph.D.
Materials Science and Technology Division
Oak Ridge National Laboratory
"Seeing into Materials through Aberration Corrected Scanning Transmission Electron Microscopy"
Friday, May 4, 2012
EMSL Auditorium - 9:00AM
The successful correction of lens aberrations has greatly advanced the ability of the scanning transmission electron microscope (STEM) to provide direct, real space imaging at atomic resolution. Very complementary to reciprocal space methods, it is especially advantageous for aperiodic systems, nanostructures, interfaces and point defects. Al-Co-Ni decagonal quasicrystals provide an excellent illustration of both the benefit of aberration correction in allowing light atom columns to be seen clearly, and the power of the direct image to reveal broken symmetry within the 2-nm clusters, the origin of the quasiperiodic real space tiling. Interfaces in complex oxide heterostructures show many surprising properties, and real space images combined with density functional calculations can reveal their origin. Aberration corrected STEM images can provide (projected) atomic coordinates with precision of a few pm. Examples will be shown of BiFeO3, mapping polarization, lattice parameter and octahedral rotations across interfaces unit cell by unit cell, and the origin of colossal ionic conductivity in SrTiO3/Y2O3-stabilized ZrO2 superlattices. Nanocrystals exhibit structures and properties with no relation to the bulk, for example the white-light emission from nanosized CdSe. Real space imaging combined with density functional calculations has unraveled the origin of such surprising properties. Finally, the direct imaging and identification of point defect configurations in monolayer BN and graphene will be presented. Such point defects create localized plasmon resonances with sub-nm localization.
James J. DeYoreo, Ph.D.
James J. DeYoreo, Ph.D.
Molecular Foundry
Lawrence Berkeley National Laboratory
"Pathways of Matrix Self-Assembly and Subsequent Mineralization"
Friday, April 20, 2012
ETB, Columbia River Room - 9:00AM
To understand the underlying physical controls governing matrix assembly and mineralization, we have investigated these processes using in situ AFM and TEM with dynamic force spectroscopy and molecular dynamics. Our results reveal the key role played by conformational transformations in controlling the pathways and kinetics of matrix assembly. Moreover, the pathway to the final ordered state often passes through transient, less-ordered conformational states. Thus, the concept of a folding funnel with kinetic traps used to describe protein folding is also applicable to matrix self-assembly. Analysis of matrix mineralization shows that nucleation is promoted through a reduction in the interfacial energy. However, nucleation via an amorphous precursor is observed at supersaturations that are too low to be explained by classical theory. The existence of pre-nucleation clusters is shown to provide a low-barrier pathway to crystallization that circumvents the large barriers to nucleation. Finally, to understand cluster- and particle-mediated crystallization processes, we have performed in situ high-resolution TEM. We show that when primary nuclei approach with a near-perfect lattice match, they undergo a sudden "jump to contact" over < 1nm. Measured translational and rotational accelerations show that strong, highly direction-specific interactions drive crystal growth via oriented attachment. Taken together, these results provide insights into the mechanisms controlling biological crystallization, from formation of the initial matrix to the maturation of final crystalline structures.
Ian McNulty, Ph.D.
Ian McNulty, Ph.D.
Center for Nanoscale Materials
Argonne National Laboratory
"X-ray Imaging at the Nanoscale"
Friday, March 23, 2012
EMSL Boardroom - 9:00AM
Over the past two decades x-ray microscopy has blossomed into a popular and rich methodology, opening the door to new research in the nanomaterials, biological, and environmental sciences. X-rays offer penetration through thick samples and exquisite sensitivity to elemental, chemical and magnetic states in buried structures. The advent of brilliant x-ray sources, nanofocusing optics, and fast dispersive and area detectors has enabled dramatic progress in instrumentation. Modern microscopes include scanning and full-field instruments with a resolution approaching 20 nm that provide a variety of contrast mechanisms and sample environments. New methods based on coherent diffraction, promising for x-ray lasers as well as synchrotrons, offer imaging beyond the limits of lenses and sensitivity to ordering and lattice strain. This talk highlights recent work at the CNM, APS, and elsewhere.
Orlando H. Auciello
Orlando H. Auciello, Ph.D.
Argonne Distinguished Fellow
Argonne National Laboratory
"Science and Technology of Multifunctional Oxide and Ultrananocrystalline Diamond (UNCD) Films and Applications to a New Generation of Multifunctional Devices/System"
Thursday, February 9, 2012
EMSL Auditorium - 11:00AM
New paradigms in the research and development of novel multifunctional oxide and nanocarbon thin films are providing the bases for new physics, new materials science and chemistry, and their impact in a new generation of multifunctional devices for micro/nano-electronics and biomedical devices and biosystems. This talk will focus on discussing the science, technology, and engineering of multifunctional oxide and nanocarbon thin films extensively investigated, developed and patented at Argonne National Laboratory during the last 15 years, and the efforts focused on integrating them into a new generation of micro/nano-electronic devices and implantable biomedical devices and biosystems.
2011
Professor Aaron Lewis
The Eric Samson Chair in Applied Science and Technology at the
Hebrew University of Jerusalem
"Nanometric Optical Imaging"
Monday, December 5 , 2011
EMSL Auditorium - 10:00AM
Work in nanophotonics began in the 1980s, before the word nanophotonics was even recognized. This work and the work of groups around the world has evolved into an exciting and rapidly growing field which has provided for nanometric optical imaging in the near-field. Even though a variety of techniques are being developed with nanometric optical imaging potential, near-field optics remains the most general method for optical characterization with resolutions at and below 100 nm. It is the only technique that can be applied to absorption, fluorescence, light collection and has demonstrated potential in non-linear imaging and Raman scattering. It is also the only optical method that provides for on-line pixel by pixel correlation with topography.
Mark Ellisman
Mark H. Ellisman, Ph.D.
University of California, San Diego
"Advancing Methods for Labeling, Staining, Imaging and Reconstructing Large Brain Tissue Volumes at High Resolution"
Tuesday, July 26, 2011
ETB Columbia River Room - 3:00PM
» Research Highlight: A Better Look at the Brain
A grand goal in neuroscience research is to understand how the interplay of structural, chemical and electrical signals in and between cells of nervous tissue gives rise to behavior. We are rapidly approaching this horizon as neuroscientists make use of an increasingly powerful arsenal of tools and technologies for obtaining data, from the level of molecules to nervous systems, and engage in the arduous and challenging process of adapting and assembling neuroscience data at all scales of resolution and across disciplines into computerized databases. This presentation will highlight development and application of new contrasting methods and imaging tools that have allowed us to see otherwise hidden relationships between cellular, subcellular and molecular constituents of nervous systems. New chemistries for carrying out correlated light and electron microscopy will be described, as well as recent advances in large-scale high-resolution 3D reconstruction with TEM and SEM based methods. The Whole Brain Catalog (WBC), a Google Earth-like open-source virtual model of the mouse brain, will also be described. The WBC is as an example of an informatics framework and web-based tool whose purpose is partly to facilitate integration of 3D image data from multiple microscopy methods and to enable the linking of information derived from other analytical approaches to imaging data shared in the publically accessible catalog.
Prof. Jingyue (Jimmy) Liu
Director, Center for Nanoscience
Professor, Department of Chemistry & Biochemistry
"Nanostructures for Catalysis and Energy Production"
Friday, May 13, 2011
EMSL Auditorium - 1:30PM
Energy is not only the driver for improving the quality of human life but also critical to our survival. To power the planet for a better future, it is imperative to develop new processes for effective use of energy and to develop sustainable and clean energy resources. Catalysis, the essential technology for accelerating desired chemical transformations, plays an important role to realizing environmentally friendly and economically feasible processes for producing energy carriers and for converting them into directly usable energy. Design and synthesis of controlled nanostructures can help us address some key issues encountered in understanding the fundamental processes and dynamics of catalyzed reactions. We have recently synthesized both nanostructured metal oxides and shape-controlled metal nanocrystals, and applied them to the systematic investigation of catalytic processes for steam reforming of alcohols and the oxidation of carbon monoxide on nanoscale facets. Aberration-corrected scanning transmission electron microscopy techniques have been used to elucidate the atomic structures of the active phases. The ability of sub-Ångström resolution imaging with in situ capabilities available in a modern aberration-corrected TEM/STEM provides us excellent opportunities to study the dynamic behavior of nanostructures and to understand their synthesis-structure-performance relationships. Recent progresses in synthesizing novel metal oxide nanostructures for energy harvest and storage will also be discussed.
MK Miller
"Atom Probe Tomography"
Materials Science and Technology Division
Oak Ridge National Laboratory
Friday, March 4, 2011
EMSL Boardroom 10:00AM
» Research Highlight: Learning to See Atoms
A brief overview of the history of the atom probe tomography (APT) technique and instruments will be presented, from the early field ion microscopy experiments in which images of individual atoms were obtained for the first time to the present state-of-the-art local electrode atom probe in which atomic resolution data sets containing billions of atoms can be obtained. Examples of the types of analyses that may be performed with this technique, including solute segregation to dislocations, interfaces, and grain boundaries, and the characterization of fine-scale precipitates in complex alloys, will be shown. A summary of APT characterizations of creep resistant and radiation tolerant nanostructured ferritic steels will be presented.
Chris Jacobsen, Ph.D.
"X-ray Imaging: Cryo, Spectroscopy and Tomography for Environmental Science"
Associate Division Director, APS XSD, Argonne National Lab
Professor, Physics & Astronomy, Northwestern University
Monday, February 7, 2011
ETB Columbia River Room - 11:00AM
» Presentation: X-ray imaging for environmental science
X-ray microscopes can image specimens that are 1-1000 micrometers thick in natural conditions, so that they nicely complement electron microscopes. New capabilities in x-ray microscopy are described: the ability to measure organic chemistry speciation at 50 nanometers resolution or better, and the ability to measure trace elements at concentrations approaching a part per billion. Enhancements to these basic capabilities include 3D imaging via tomography, the correlation of heavy elements with soft material ultrastructure, and the use of cryogenic specimens to minimize the effects of radiation damage. These and other advances in synchrotron-based x-ray imaging will be described.
Howard Padmore
Division Deputy for Experimental Systems Advanced Light Source
Lawrence Berkeley National Laboratory
"Photocathodes for Free Electron Lasers"
Thursday, January 13, 2011
EMSL Auditorium - 1:30PM
» Research Highlight: Shining Light into the Dark Places of Science
Free Electron Lasers (FELs) have a peak brightness well over 1010 times that of a 3rd generation synchrotron and can produce fully coherent ultra-fast x-ray pulses into the sub-fsec regime. As such, FELs represent the ideal source for examining matter on fundamental length and time scales. The next evolution of FELs will involve increasing the repetition rate into the MHz regime, increasing the time averaged flux and the number of experiments that can simultaneously operate at the same time reducing the physical scale and therefore cost of the machine to the minimum possible.
The performance of an FEL is directly linked to the quality of the electron beam; typically this beam is produced by a laser-driven photocathode, before acceleration to relativistic velocity in a linear accelerator. A lower emittance beam can be used to lase at higher energy, or can be used to reduce the physical scale of the FEL, by reduction of the electron energy and hence the length and cost of the accelerator.
In this talk, I will give an overview of FEL physics as it affects photocathode design and show how through engineering of the electronic structure of the photocathode, potentially huge advances can be made in FEL performance.