Density: Helium Pycnometry

Micromeritics Accupyc II 1340 measures the skeletal volume of a material by gas displacement using the volume-pressure relationship of Boyle’s Law.  An inert gas, typically helium, is used as the displacement medium.  The sample is placed in a sealed cup of a known volume.  This cup is then placed into the sample chamber.  Gas is introduced to the sample chamber and then expanded into a second empty chamber with a known volume.  The pressure observed after filling the sample cell and the pressure discharged into expansion chamber are measured, and then the vol

Contact Angle

When the contact angle of a drop in a surface is over 90° the surface is referred as hydrophobic, which refers to poor wetting. When the angle is below 90° the surface is referred as hydrophilic. Contact angle is often used to measure cleanliness, roughness, absorption, surface heterogeneity, among other properties.

Auger Electron Spectroscopy (AES)

Auger electrons emitted from the surface are drawn into a spectrometer that ultimately measures their kinetic energy distribution. The technique is inherently surface sensitive because the Auger electrons typically have low kinetic energies (<3kv). The Auger spectra contain information about the concentration and (sometimes) the chemical environment of surface and near-surface atoms. Greater depths (up to a few microns) can be probed by coupling the technique with ion milling. Lateral distributions of elements can be measured with sub-micron resolution.

AFM: Atomic Force Microscopy

An Atomic Force Microscope (AFM) provides 3-dimensional topographic information about a sample by probing its surface structure with a very sharp tip. The tip is scanned laterally across the surface, and the vertical movements of the tip are recorded and used to construct a quantitative 3-dimensional topographic map. The lateral resolution of the image can be as small as the tip radius (typically 5-15 nm), and the vertical resolution can be on the order of angstroms.

Raj Kothapalli

Sri-Rajasekhar (Raj) Kothapalli

Associate Professor of Biomedical Engineering

(e) szk416@psu.edu
(o) 814-865-0459
325 Chemical and Biomedical Engineering Building

https://sites.psu.edu/biophotonicsandultrasoundimaginglab/