October 2011, Issue 3 - Product Innovations. The World's Fastest AFM - Dimension FastScan

Professor Paul Hansma, Co-Chair of Physics Dept., UCSB, and pioneer of AFM instrumentation, remarked, “The recent development of high-speed AFM by Bruker is a real breakthrough. I am impressed by Bruker's commitments in research and development to bring this to the AFM community.”

“The development of the recent high-speed AFM by Bruker is a real breakthrough,” agreed Professor Christoph Gerber, Director for Scientific Communication of the NCCR Nanoscale Science at the Institute of Physics, University of Basel, Switzerland, and co-inventor of atomic force microscopy. "It has opened the door to the next revolution of nanoscience, particularly in new areas such as structural biology.”

BR self-assembles into Purple Membrane patches on a mica surface under the right buffer conditions.

The movie shows the dynamic edge of two adjacent patches, integration of small patches, and the addition of further BR during continuous imaging. The data was obtained by the combined capability of low amplitude (2nm) Peak Force Tapping™ (PFT) in fluid, and the increased imaging bandwidth enabled by the Dimension FastScan AFM, and small Broadband cantilevers.

• PFT achieved resolution typical for Contact Mode, and beyond TappingMode
• PFT simplified force control, due to it’s immunity to thermal force drift
• FastScan speed enabled the study of sample dynamics

The combination of fast, high resolution imaging, multi-sample automation, SmartEngage, and ScanAsyst® based feedback self-optimization enables a new level of productivity in a number of research and development applications. This new capability can be used to search for samples with certain properties, or (in combination with the 25MPixel capability) for high data content survey runs of e.g., 25 samples overnight. It also lends itself to multi-sample screening of nanoscale properties, e.g., in polymer or pharma formulation, and is well adapted for technician-operated lab environments.

This is a 1um x 1um image, 256 line, taken AT 100HZ. The frame rate is 2.5 seconds. What you can see in the movie is the detail of the lamella forming as the crystallization front moves to the left. We can also see how the lamella move around and incorporate defects.  At the 0.29 second mark you can see the two fronts coming towards each other, passing over defects, sometimes incorporating them, sometimes not. You can also see how when the lamella pass this larger defect that some terminate while others go around. Ultimately, the two fronts join, and in some regions the lamella join, and in others an interface is created.

In-situ recording of a 5nm thick polystyrene film (molecular weight 4.2 kg/mol) de-wetting a hydrophobic Si wafer at 55, 65 and 75-Degree C.

The experiment is conducted in air, on top of a Dimension heater/cooler. When the sample temperature passes the polymer’s glass transition temperature (Tg), it starts to behave like a viscous fluid. The de-wetting process can now be observed. The speed of the process is temperature dependent. De-wetting always involves the formation of holes in the film, which grow and join, leaving linear structures which finally rupture and form droplets.