
| Associate Division Director,
X-ray
Science
Division Advanced Photon Source, Argonne National Laboratory 9700 S. Cass Avenue Argonne, IL 60439-4837, USA Office: 401-C4239 Phone +1-630-252-7960 Email: cjacobsen@anl.gov
Interim Group Leader, Detectors Group Senior Physicist |
Professor, Department of
Physics & Astronomy Northwestern University 2145 Sheridan Road Evanston, IL 60208-3112, USA Office: Pancoe 4105 Phone +1-847-467-2703 Email: c-jacobsen@northwestern.eduFaculty member, Graduate Program in Applied Physics Faculty member, Chemistry of Life Processes Institute |
Chris Jacobsen's research
group is focused on developing new methods in x-ray
microscopy, and applying them to interesting problems in biology,
environmental science, and materials science. Using either
diffractive optics (like Fresnel zone plates fabricated using
electron beam lithography), or lensless methods where iterative
phase retrieval methods are used to reconstruct an image from a
coherent diffraction pattern, images with a spatial resolution of
30 nm or better can be obtained. In absorption contrast, one
can combine imaging with spectroscopy to study chemical speciation
at the nanoscale, or one can use fluorescence detection to study
trace element distributions with parts-per-billion
sensitivity. We are also developing detectors and image
reconstruction algorithms that can be used to obtain quantitative
phase contrast images with hard X rays, and thus put elemental
distributions into their ultrastructural context and also go from
measurements of content to measurements of concentration (since
concentration gradients drive chemical processes). Finally,
we are interested in understanding the limitations that radiation
damage presents to x-ray microscopy studies, and in developing
both cryo instrumentation and sample preparation methods to
mitigate those limitations. These efforts require bright
x-ray beams, so we use synchrotron radiation sources at Argonne
Lab, Berkeley Lab, and elsewhere. Students in the group
explore interesting problems in optical physics and in
instrumentation, and get to broaden their perspective by working
with collaborators from other research fields like biology,
environmental science, and materials science.
Representative publications:
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