We are in the process of setting up two experimental set-ups.
STM 1 is a 4K, UHV system that we moved from MIT. However, we are upgrading it to run on a cryocooler, replacing the use of liquid helium for cooling
STM 2 (SNIPE) is an ultra-low temperature, high magnetic field SPM system. More information about the development of this system can be found here.
With a tip-sample separation of about 10 angstroms, eliminating vibrations is a necessity. We have gone to great lengths to reduce potential vibrations including supporting our experiment on a two ton granite table top, using air springs to float the table during measurements, setting the entire system in the ultra-low vibration basement area of the Millenium Science Complex at PSU, and finally employing an in situ spring system for the microscope itself.
Atomic Resolution and Spectroscopic Stability:
Both of these are achieved through vibration damping and electronic noise reduction. Atomic resolution is imperative to pinpoint a location of interest and understand spatial variations in spectroscopic measurements.
Using a Cryomech PT-407 Pulse Tube cryocooler, we have the ability to vary the microscope and sample temperatures from 4K to room temperature. This allows for studies above and below critical temperatures. In addition, we have overcome drift issues which have plagued other variable temperature STMs and are able to follow the same atomically resolved region as a function of temperature. With this ability, we can see changes at specific atom sites as we pass through critical temperatures.
Our entire STM 1 setup and custom built STM are shown. Note that the set-up view is its previous incarnation, at MIT. For more details, here is an e-drawing file of our entire system. Please note that a e-drawing viewer is needed to open the file. An e-drawing viewer can be downloaded from here.
Feb 4, 2014