Scanning transmission x-ray microscope for materials science spectromicroscopy at the ALS

Technical Report · Tue Apr 01 04:00:00 EST 1997

DOI:https://doi.org/10.2172/603496· OSTI ID:603496

Warwick, T.; Seal, S.; Shin, H. ^[1]

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1. Ernest Orlando Lawrence Berkeley National Lab., CA (United States); and others

The brightness of the Advanced Light Source will be exploited by several new instruments for materials science spectromicroscopy over the next year or so. The first of these to become operational is a scanning transmission x-ray microscope with which near edge x-ray absorption spectra (NEXAFS) can be measured on spatial features of sub-micron size. Here the authors describe the instrument as it is presently implemented, its capabilities, some studies made to date and the developments to come. The Scanning Transmission X-ray Microscope makes use of a zone plate lens to produce a small x-ray spot with which to perform absorption spectroscopy through thin samples. The x-ray beam from ALS undulator beamline 7.0 emerges into the microscope vessel through a silicon nitride vacuum window 160nm thick and 300{mu}m square. The vessel is filled with helium at atmospheric pressure. The zone plate lens is illuminated 1mm downstream from the vacuum window and forms an image in first order of a pinhole which is 3m upstream in the beamline. An order sorting aperture passes the first order converging light and blocks the unfocused zero order. The sample is at the focus a few mm downstream of the zone plate and mounted from a scanning piezo stage which rasters in x and y so that an image is formed, pixel by pixel, by an intensity detector behind the sample. Absorption spectra are measured point-by-point as the photon energy is scanned by rotating the diffraction grating in the monochromator and changing the undulator gap.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 603496
• Report Number(s): LBNL--39981; ON: DE97007345
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
43 PARTICLE ACCELERATORS
ADVANCED LIGHT SOURCE
DESIGN
MICROSCOPES
PERFORMANCE
PHOTON TRANSMISSION SCANNING
X RADIATION