August 2012, Vol. 2 - The World's Ultimate AFM

Achieving atomic resolution with atomic force microscopy has been a goal of the community since the invention of the technique. There are a number of great results from academic laboratories (Fukuma et. al., Hoogenboom et. al., Gross et. al.) that have demonstrated this by systematically lowering the noise of their systems, however, this has usually been accomplished by moving to restrictive small sample platforms and small cantilevers.

Bruker took on the challenge of achieving atomic resolution with a more productive, large-sample atomic force microscope (AFM) platform that is commercially available and uses standard cantilevers. The focus was to develop an approach with no compromises; it had to still offer the fastest available throughput, accommodate large samples, and perform all the useful SPM modes. Our continual pursuit of new technologies enabled Bruker to move forward from our initial invention of TappingMode™ to develop Peak Force Tapping®, which in turn, led to our ability to break this long-standing atomic resolution barrier.

Now, Peak Force Tapping and ScanAsyst® are rapidly becoming industry standards that enable our Dimension and MultiMode® 8 AFMs to capture atomic resolution using standard production systems in lab environments, while still providing the ultimate in AFM productivity and ease of use.

High-performance AFMs are frequently used to collect images of atomic lattices, but achieving images with single atomic defects in normal atmosphere environments has been traditionally much more difficult since they require much better control of the force between the tip and sample. Peak Force Tapping utilizes piconewton force control to simultaneously capture atomic resolution images and mechanical maps. It is particularly noteworthy that this level of performance has been obtained on a large-sample platform with standard cantilevers (TESPA, SNL+, FastScan B).

See the attached link for an image of the cleavage plane of calcite taken with the Dimension FastScan™ using a standard cantilever (SNL+, 60um) in water. In the image you can see two crystal planes (brown and blue) separated by the dissolving crystal front (red). We have overlaid the atomic model of the oxygen atoms in the calcite on the lower plane, and there you can see the zig-zag structure revealed in the image. You can also see the individual defects in the crystal near the dissolution plane as well as a secondary facet brought out on the etch front.

An example on Calcite and Mica.

Atomic Resolution and Atomic PeakForce Capture

• Peak Force Tapping utilizes piconewton force control to collect atomic resolution images

Highest Performance and Quantitative Nano-Mechanical Mapping on Any AFM Sample

• PeakForce QNM® enables quantitative mechanical property measurements at the atomic scale
• Sample from subnanometer to 100s of nanometers in height [While this is a true statement for Icon, the sample is not 100’s nm high]

The right and bottom-right image (Calcite, Dimension Icon, Height and Stiffness Channels,) demonstrates Peak Force Tapping's ability to deliver atomic resolution imaging while simultaneously providing real-time maps of properties derived from the individual force interactions. In this image pair, the atoms are visible in the height channel, but the stiffness map show that alternate rows of atoms have significantly increased contact stiffness.

The left and bottom-left image (Mica, MultiMode 8, Height and Adhesion) also shows atomic resolution but now in conjunction with the adhesion channel. In the height image, individual atomic features are revealed, while the adhesion force channel highlights differences in the maximum attractive interaction force between individual atoms and the tip.

Standard Cantilevers

Use standard cantilevers and large samples; short cantilevers are not required. For more information on how Atomic PeakForce Capture enables this level of performance, watch Bruker's latest webinar Atomic Imaging with Peak Force Tapping, or visit www.bruker.com/Fastscan to see additional atomic images, videos, and atomic scale force spectroscopy curves.

Have a question on Dimension FastScan contact us at productinfo@bruker-nano.com.

Footnote
All data was acquired in fluid, by Bede Pittenger & Yan Hu of Bruker Nano Surfaces, and Daniel Ebeling of the University of Maryland, in the Santa Barbara laboratories of Bruker's Nano Surfaces Division.