Core Facilities Funding Enhances NUANCE Center Facilities in 2009

Users of EPIC, NIFTI and Keck-II stood to benefit by the fall 2008 awards from Northwestern University's Core Facilities Funding Committee.

EPIC

The Electron Probe Instrumentation Center (EPIC) purchased a double tilt
heating stage sample holder for the JEOL 2100F high-resolution analytical transmission electron microscope. Another critical capability now has been added to the microscope—the ability to perform nano-structure characterization at controlled and elevated temperature. With the heating stage, specimens can be heated inside the TEM to 1000°C in less than a minute. In situ heating transmission electron microscopy is a powerful tool for understanding the effects of temperature on materials.

The new sample holder allows users to study the thermal stability of nanocrystalline materials, in situ nucleation and phase transformation, size dependence of temperatures, the melting and crystallization process and defects (e.g. dislocation loop) formation and growth in alloys. A double tilt holder, which
allows the specimen to be tilted about two perpendicular axes with respect to the electron, is essential to resolve structure of nano-materials. Unlike a single tilt holder, the specimen can be studied along a wide range of orientations which contain reliable 3D information.

For more information, contact Shuyou Li.

NIFTI

Core faciities funding allowed the NIFTI facility to upgrade the Veeco Multimode Scanning Probe Microscope with a variable temperature stage and high speed Nanoscope V controller. The flexible controller enables up to eight images to be simultaneously displayed in real-time with unprecedented signal-to-noise ratio, provides thermal tune measurements of cantilever resonances up to 2 MHz and easy access to input and output signals for multiple image and data analysis. The DSP operates at 300 MHz resulting in much faster response time and less tip wear. Users will enjoy built-in Q control and phase imaging and simplified operation via “Easy-AFM” software, which has routines for producing images at the push of a button (especially helpful for new or infrequent users). The NanoScope V controller allows the user to operate several advanced SPM capabilities, including piezoresponse force microscopy (PFM), scanning capacitance microscopy (SCM), conducting AFM, scanning spreading resistance microscopy (SSRM), pico force spectroscopy and nanolithography.

The addition of variable temperature system capabilities enables measurements of material structure and mechanical properties on materials at the nanometer scale. With new Auto-Z engage and heated tip-sample control, some of the advanced SPM techniques can be done at variable temperatures, including magnetic force microscopy, piezo response and electrostatic force microscopy. Materials like polymers, exhibit phase transitions when heated, and cells and molecules function only in narrow temperature bands.

For more information, contact Gajendra Shekhawat.

Keck-II

Keck-II is adding a high resolution Dektak 150 Surface Profiler from Veeco, which maps surface topography by dragging a sharp probe across a sample surface. A profilometer uses a mass cantilever system to keep the tip force constant while scanning. Profilometers utilize the same imaging fundamentals as a scanning probe microscopy, but with a much larger tip (i.e. 2.5 microns in diameter). The larger tip limits the vertical and horizontal resolution. The probe tip is usually made of diamond to reduce tip wear. Profilometers are typically used to measure surface roughness or film thickness. Modern profilometers, such as this model, are capable of creating 3-dimentional topographical surface maps rather than traditional line scans. The capabilities of this profilometer support other major capabilities of Keck-II, such as XPS and ToF-SIMS where quantitative measurements of surface profile are required.

For more information, contact Xinqi Chen.