Site Details Other Information Basic Energy Sciences Directorate |
CFN End Stations at NSLSManaged by: CFN end stations at NSLS are dedicated to: (1) small-angle x-ray
scattering (SAXS) and grazing-incidence small-angle x-ray scattering
(GISAXS) measurements on NSLS beamline X9 and (2) combined low-energy
electron microscopy and synchrotron-based photoelectron microscopy
(LEEM-PEEM) measurements on NSLS beamline U5UA. Proposals for beam time to
carry out nanoscience measurements for on these beamlines are submitted
through the CFN website for SAXS/GISAXS and through NSLS on-line
Proposal,
Allocation, Safety, and Scheduling (PASS) system for LEEM-PEEM. If the
proposal PI is a registered CFN User, then the proposal is also eligible for
CFN Contributing User beam time, which amounts to 25% of the available beam
time. Highest rated proposals are given priority in allocating beam time. CFN SAXS/GISAXS endstation at NSLSContact: Kevin Yager kyager@bnl.gov The X9 undulator beamline is a joint venture between the NSLS and the CFN. The endstation is a cutting-edge x-ray scattering instrument, which can probe material structure at the molecular- and nano-scale. Specifically, X9 is capable of performing simultaneous small-angle (SAXS) and wide-angle (WAXS) x-ray scattering measurements, including reflection-mode analysis (GISAXS and GIXD). This wide q-range enables simultaneous quantification of the size, order, and orientation of molecular/crystal packing, and nanostructure. It can study crystals, powders, solutions, and soft materials; with control of sample environment (air, vacuum, liquid, etc.) and temperature. The instrument allows for probing of surfaces, thin films and buried interfaces.
The x-ray energy can be tuned from ~8 to ~18 keV, providing access to a wide range of wave vectors, and thus size-scales, as well as supporting resonant scattering at edges of particular interest to hybrid materials. The instrument can measure from a q of 0.002 A^-1 (structures as large as 300 nm) to a q of 4 A^-1 (structures as small as 1.6 Angstroms). The instrument provides microbeam SAXS capabilities (beam focus as small as 20 microns) for study of small sample, inside capillaries or microfluidics, or even inside individual micro-droplets. The undulator source provides high flux, enabling experiments that would take days on a lab x-ray instrument to be performed in seconds.
The X9 instrument is currently being actively used to study a variety of
materials and challenging scientific problems. The instrument is in heavy
demand for x-ray scattering from solutions of proteins and other
biomolecules, as well as for characterization of supramolecular structures
and nanoparticle lattices in solution. The reflection-mode capabilities are
ideal for study of nanostructured thin films, including block-copolymers and
lithographic patterns. Hybrid and hierarchical materials can also be studied
in detail. For instance, the structure and crystalline orientation of
heterogeneous materials used for organic solar-cells can be studied using
X9, including probing the effect confining patterns and thermal history
in-situ. CFN LEEM-PEEM endstation at NSLSContact: Peter Sutter The undulator beamline U5UA hosts a commercial low-energy electron microscope (LEEM III, manufactured by Elmitec) equipped with an electron energy analyzer so that it can also be used as a photoemission electron microscope (PEEM) operating in ultra-high vacuum (UHV). The sample is illuminated either by an electron beam or by monochromatic focused soft x-ray radiation with tunable photon energy (15-150 eV) and a vertical beam size of 30-50 microns. Modes of operation include mirror electron microscopy (MEM), bright-field and dark-field low-energy electron microscopy (LEEM), low-energy electron diffraction (LEED), x-ray photoelectron spectroscopy (XPS), and x-ray photoelectron emission microscopy (XPEEM). In XPEEM pilot experiments, a lateral resolution better than 80 nm with a photoelectron energy resolution of about 0.3 eV has been achieved. For LEEM (lateral resolution 10-20 nm) and LEED, samples must be crystalline (single-crystals are preferred) and conducting (metal or semiconductor). The sample holder allows heating by electron bombardment or can be cooled by LN2, enabling sample temperatures between 200 K and about 1800 K. Current research topics include epitaxial growth of metal and semiconductor nanostructures, and surface chemistry/catalysis on metals and metal oxides under UHV conditions. For in-situ MBE growth experiments in the microscope chamber, up to two evaporators (2.75” outer flange diameter, Omicron style) as provided by the user may be installed.
Last Modified: % Response.Write (FileLastMod()) %>
|