Scanning Probe Microscopy at Mount Holyoke College

Katherine Aidala
Associate Professor of Physics
211 Kendade Hall
Mount Holyoke College
50 College Street
South Hadley, MA 01075
email: kaidala@mtholyoke.edu



Current Projects

Ferromagnetic Nanorings and Nanowires
In collaboration with Prof. Mark Tuominen (UMass)
Researchers: Jessica Bickel, Mina Khan, Madeline Shortt, Fikriye Idil Kaya, and Wenming Ju (UMass)

Nanoscale magnets exhibit unique magnetic states that can be used as novel data storage devices. Magnetic nanorings offer a unique state that has no poles, but instead could store the “1” and “0” as clockwise or counterclockwise magnetic fields in what is called the “vortex” state. The project directly explores the switching of the vortex state by passing a current through the tip of an atomic force microscope. This current will produce an azimuthal magnetic field that controls the vortex chirality. Simulations predict that azimuthally applied fields result in interesting states beyond the vortex, generating stable 360 degree domain walls.

Topography (left) and MFM (right) of symmetric (top) and asymmetric (bottom) Co nanorings in the "onion" state.

Mechanical Characterization of Hydrogel Thin Films
In collaboration with Prof. Ryan Hayward (UMass)
Researchers: Ye Tian

The processing of hyrogel thin films can result in dramatically different mechanical properties. Using the AFM we can characterize the Young's Modulus and better understand the effect of processing on such properties. The ultimate goal of this project is to fold gels into desirable structures via "oragami" methods based on different mechanical properties of the gels.

From Kim et al. Soft Matter 8 (2012) 2375.

Physical Properties of Native Bacterial Biofilm Cells
In collaboration with Prof. Megan Nunez (MHC)
Researchers: Ye Tian

We are using the AFM to characterize the stiffness of bacteria in order to understand adhesion and growth of these cells. Former group members and collaborators studied the physical properties of five kinds of bacteria living in simple biofilm communities on a glass surface. Notably, the biofilm-forming cells have a high cellular spring constant, indicating that they are quite stiff and hinting that stiff bacteria may preferentially colonize surfaces in the early stages of biofilm formation.


Charge and Transport in Quantum Dots and Quantum Dot/Organic Hybrid Materials
Researchers: Jason Moscatello, Karishma Reddy Khan, Sarah Read, Morgan Patterson, Xiaofan Xu, Pheona Williams

Nanocrystal quantum dots (NQDs) are crystalline formations of material that exist on the nanoscale, giving them very unique optical and electronic properties that can be tuned by altering the dot size and material. These properties are currently put to use in technology such as LEDs, photodetectors, solar cells and lasers. However, the manner in which charges move through arrays of NQDs is dominated by disorder, and strongly influenced by the immediate environment, which inhibits taking full advantage of the material. In order to more fully understand NQD systems with the goal on improving the performance/efficiency of NQD-based devices, we use AFM techniques called Electrostatic Force Microscopy (EFM) to study just how the charges move in (sub)monolayers of NQDs.

PotentialMapTopography of a QD film on SiO2 between two Au electrodes; the surace is overlaid with an EFM colour potential map.