Tech Briefs

Microscope produces tiny beam down to 10nm

The need to image nanostructures and chemical reactions down to nanometer resolution requires a new class of x-ray microscope that can perform precision microscopy experiments using ultra-bright x-rays. The National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory, has designed such an instrument, which can deliver a suite of unprecedented x-ray imaging capabilities.

Fig. 1 – Multi-layer Laue lens module inside the vacuum chamber of the microscope installed at the Hard X-ray Nanoprobe beamline.

The microscope manipulates novel nanofocusing optics called multilayer Laue lenses (MLL), extremely precise lenses grown one atomic layer at a time, which produce a tiny x-ray beam about 10 nanometers in size. Focusing an x-ray beam to that level means being able to see the structures on that length scale, such as proteins in a biological sample. (See Figure 1)

The scientists who built this microscope are working toward making the focused x-ray beam spot even smaller in the future. The new microscope produces x-ray images by scanning a sample while collecting various x-ray signals emerging from the sample. Analysis of these signals helps researchers understand crucial information about the materials they are examining: density, elemental composition, chemical state, and the crystalline structure of the sample.

Getting a clear image at this scale requires extremely high stability of the microscope to minimize vibrations and to reduce possible thermal drifts, changes in the microscope due to heat. It requires more than 20 piezo motors, which produce motion when electric currents are fed into piezo crystals, controlled down to nanometer-scale precision, squeezed into a tight space, to meet its functionalities.

“This instrument incorporates most recent developments in interferometric sensing, nanoscale motion, and position control. Recorded drifts of two nanometers per hour are unprecedented and set a new benchmark for x-ray microscopy systems,” said Evgeny Nazaretski, a physicist at NSLS-II who spearheaded the development of the microscope.

After construction, the MLL module was tested at the Diamond Light Source Beamline I-13L for extensive x-ray performance measurements, which confirmed its stability and reliability. The xray microscope will be available for user experiments later this year.