X-Ray Microscopy

Structural & Morphology Characterization (X-ray analysis)

Due to the upcoming SLS 2.0 upgrade this technique will be unavailable at PSI until further notice.

STXM is a non-invasive x-ray microscopy technique that can be employed for the space-, time- and spectroscopically-resolved investigation of micro- and nanostructured materials. In this technique, the sample under investigation is positioned in the focal spot of a focused x-ray beam, and the transmitted x-ray intensity is recorded with a suitable detector (typically, a photomultiplier tube or an avalanche photodiode). To acquire STXM images, the sample is raster scanned with a piezoelectric stage, and the transmitted intensity is recorded at each point of the scan.

Thanks to the use of x-rays as the probing mechanism, STXM allows easy access to a number of x-ray spectroscopic contrast mechanisms that allows imaging with quantitative sensitivity to not only the elemental composition, but also the chemical state of the sample material (i.e. oxidation state and/or molecular structure), with relatively low radiation damage. Furthermore, images with magnetic sensitivity can be acquired with STXM when illuminating the sample with circularly polarized x-rays, or with sensitivity to molecular orientation with linearly polarized x-rays.

Typical STXM images exhibit a spatial resolution on the order of 10-20 nm, depending on the Fresnel zone plate employed for the focusing of the x-rays. The lateral size for typical STXM images is on the order of 1-100 µm. Finally, if an avalanche photodiode is employed as detector, time-resolved STXM images with a temporal resolution down to 100 ps can also be acquired.

          provided at Large Scale Facilities by:
STXM - Nano-XAS Beamline @ Swiss Light Source Synchrotron
The NanoXAS endstation consists of a scanning transmission X-ray microscope (STXM) in combination with a scanning probe microscope (SPM). By combining these techniques, the NanoXAS is able to obtain elemental and chemical composition, oxidation states, molecular orientation, topography, surface forces, as well as electric and magnetic properties on a variety of specimens with nanoscale resolution
Bending magnet, polarization linear horizontal, circular (right, left), focus size ~ 40nm, flux 1x1013 ph/s @ 300 eV
270-1800 eV
Si avalanche photodiode (APD): transmission measurements; channeltron: surface sensitive electron detection can be performed simultaneously with x-ray transmission measurements; scanning probe tip; non-standard detection upon request
Spectral resolution >3000
Spatial resolution ~40 nm
Closed-loop piezo scanner, range 40μm x 40μm x 6μm
Room temperature or resistive heating
UHV sample chamber vacuum (10-8 mbar)
A number of zone plates is available
Scanning Probe Microscopy (SPM)
STXM - PolLux Beamline @ Swiss Light Source Synchrotron
PolLux has a scanning transmission X-ray microscope (STXM) endstation, which is capable of producing high resolution images (better than 50 nm) and soft X-ray absorption spectra of very small sample areas; by combining imaging and spectroscopy, PolLux can map out properties such as elemental and chemical composition, molecular orientation, oxidation states, magnetic domains as well as thickness variations with high resolution
Bending magnet, polarization linear horizontal, circular (right, left), focus size < 40nm
250-1600 eV
Photomultiplier tube with a phosphor screen: standard detector with high efficiency over a wide range of energies; Si avalanche photodiode (APD): narrow pulses that enable time-resolved images; fast camera (CCD): a phosphor screen close to the sample, with transfer optics allow "differential phase contrast" type imaging with an out-of-vacuum fast CCD; channeltron: total electron yield (TEY) detection of sample surface can be performed simultaneously with transmission measurements with the PMT
Spectral resolution >3000
Spatial resolution <40 nm
Temperatures -20oC to 100oC
Sample chamber vacuum (10-6 mbar) to 1 atm, inert gas or He
Magnetic field up to 200mT, optical microscope, a number of zone plates is available
Soft X-ray Microscope
It is devoted to cryo nano-tomography in the water window and multi-keV spectral regions (E= 270 eV–2600 eV) for biological applications. In addition, spectroscopic imaging (a series of 2D images over a range of X-ray wavelengths) at several interesting X-ray absorption edges can be performed.