Complementary Tools for Teaching Physical Chemistry

An Interview with Dr. Howard Fairbrother at Johns Hopkins University

Seniors in Chemistry and Chemical Engineering get hands-on experiences with complementary microscopy instruments at Johns Hopkins University. In the Advanced Microscopy lab module, students have a great “opportunity to do laboratory work and run instruments they might use in graduate research or careers in industry,” explains Professor Howard Fairbrother.

Recently the university expanded the undergraduate facilities, providing an opportunity to introduce new equipment for chemistry laboratory classes. Familiar with the high resolution microscopes provided by Nanoscience Instruments for education, Professor Fairbrother proposed a package of complementary techniques to expose students to advanced microscopy. In addition to seeing materials across a range of magnifications, it was important that the instruments be easy to use and provide data quickly, given time constraints in a laboratory classroom setting. The all-in-one atomic force microscope (AFM), scanning tunneling microscope (STM), and desktop scanning electron microscope (SEM) are a perfect fit for these requirements.

“Students are excited from the hands-on experience they get in the lab.”

The Phenom SEM has a user-friendly interface so students can quickly take images. With a magnification range from 70x to 20,000x,* the Phenom Pure SEM bridges the visible world to the nanoscale world. The Phenom SEM has an optical image correlated to the electron image. Using this optical navigation, a location of interest on a sample can be chosen. Within 30 seconds, electron microscopy images showing a mixture of polystyrene spheres and gold particles are displayed for the Advanced Microscopy students.

Phenom SEM topography mode image of polystyrene and gold particles from JHU advanced microscopy labPhenom SEM topography mode image of polystyrene and gold particles
from JHU Advanced Microscopy lab

Because the Phenom SEM has a backscattered electron detector, the material contrast is readily apparent to differentiate polystyrene versus gold. Students also see the size difference of polystyrene compared to the gold particles in the SEM. Imaging starts around 4000x, then magnification is increased to over 18,000x to see the gold nanoparticles. The same samples are then imaged in the AFM, which provides another demonstration of size and magnification.

 Atomic force microscope image of gold nanoparticles, scan size 10 microns, from JHU Advanced Microscopy lab

Atomic force microscope image of gold nanoparticles, scan size 10 microns,
from JHU Advanced Microscopy lab

AFM and STM are the eyes into the nanoscale world. AFM is used to evaluate devices and structures as product dimensions are shrinking. The STM can reveal atomic structure, terraces and steps. Visualizing atoms is a truly unique experience for students.

Having an STM in the lab allows young scientists and engineers to image carbon atoms at the atomic scale using highly oriented pyrolytic graphite (HOPG).

Hands-on instruments in Advanced Microscopy lab at Johns Hopkins University

Hands-on instruments in Advanced Microscopy lab at Johns Hopkins University


* Current specification for Phenom Pure SEM magnification is up to 30,000x with an option up to 65,000x.

Photo Credit: Miranda J. Gallagher