Dr. Eubank demonstrates how the new x-ray machine works.
Aug 29, 2016
To the frequent traveler, or students fresh off a Junior Journey trip, the term “x-ray” may be synonymous with TSA security checks. To others, it may conjure up painful memories of broken bones, as it does for my wife, who sustained a dual spiral fracture in her leg while playing flag football a number of years ago.
More likely, it may drum up thoughts of the iconic hazard symbol or the classic monochromatic skeletal images that can be intriguing, informative, and educational to faculty like Dr. Mick Lynch, Professor of Athletic Training and Clinical Ed. Coordinator, to pre-med or pre-vet students, or even pre-dental students (think back to those wonderful visits to the dentist to view your cavities or impacted wisdom teeth).
However, to a chemist, concepts like wavelength, energy, and electromagnetic radiation may come to mind instead. Most people are aware that x-rays are useful in the medical field, because they allow us to see through less dense objects, like skin and muscle, to reveal the more dense bones within. What they may not realize is that this is possible because of the high energy of x-rays (and corresponding very short wavelengths, compared to visible light and even UV light). It is this wavelength that is of interest to many materials scientists.
The wavelength of x-rays is directly in the range of the length of many chemical bonds (i.e., the distance between two atoms in a molecule, like water or caffeine), which allows us to “see” the arrangement of atoms in a molecule and molecules in a compound, or, more specifically, in a crystal thereof. Without going into too much detail, there have been numerous techniques (and mathematical calculations) developed that utilize the way x-rays diffract through a crystalline sample (e.g., salt or sugar) to give information on the atomic and molecular make-up and arrangements within that material. In many cases, the information can be transformed into a three-dimensional picture of the sample, much like the more familiar CT scans in the medical field.
In fact, the now-famous double-helix structure of DNA, which led to the 1962 Nobel Prize in Medicine for Watson, Crick and Wilkins, was partially discovered utilizing this crystallographic technique. Thus, we can see the broad scope of such an interesting technique, spanning multiple disciplines from chemistry to biology to medicine and beyond.
Over the summer, a generous donor, the Ting Tsung and Wei Fong Chao Foundation, provided funds to support the purchase of a new scientific instrument that takes advantage of x-rays, a powder x-ray diffractometer (PXRD), for the Department of Chemistry, Biochemistry, and Physics.
After reviewing several instrument models from numerous companies, the department decided on the D2 PHASER PXRD with LYNXEYE detector from Bruker, an excellent benchtop instrument (touted as “the world's fastest desktop x-ray diffractometer”), which allows for ease of installation, mobility, and better access for demonstrations and teaching within our lab and research courses. In addition, two department faculty will travel to Bruker for in-depth training on the instrument, which will help foster the development of more course experiments and projects that can utilize this exciting instrument and corresponding techniques.
At FSC, the department previously had to send their crystalline samples externally, but now faculty and students have direct access to a state-of-the-art instrument. The new PXRD was installed over the summer and has already found use in ongoing summer research projects. My faculty/student collaborative research student, Juan Garcia, began using the instrument for his project, Hybrid Materials for Biomedical Applications, to distinguish between his starting material and the crystalline product, an anti-HIV drug analogue. Another of my research students, Eric Alonso, was able to monitor the air-induced degradation of his cobalt MOF product using the PXRD. In addition, Dr. Carmen Gauthier’s high school research student, Nate Senn, was able to utilize the instrument to confirm the identity and purity of a series of targeted nanoscale metal-organic polyhedral materials.
As we have already indicated, x-ray diffraction is a fascinating technique utilized not only in chemistry, but also in numerous areas of science, research, and industry alike. For example, in the pharmaceutical industry the technique can be used to distinguish between polymorphic phases of drugs, which is key in determining assignment of patents and biological effects like solubility, site-specific targeting, and effectiveness of many medicines. Similarly, XRD techniques are utilized for quality control of crystalline samples in the solar, ophthalmic, and semiconductor fields, among others.
Aside from research and industry, the addition of the powder x-ray diffractometer provides a new educational tool for the department, allowing us to not only teach, but demonstrate core concepts in organic chemistry, inorganic chemistry, materials characterization, and beyond. We are excited for students to begin their x-ray adventures over the coming years.
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