In November 1895, German physics professor Wilhelm Conrad Roentgen was in his laboratory studying light phenomena generated by discharging an electrical current in a vacuum glass tube when, to his utter disbelief, he suddenly saw the bones of his hand outlined through his flesh.
Roentgen had discovered X-rays. Within weeks, physicians were using these magical rays to see inside the human body and less than three months later, 14-year-old Eddie McCarthy of Massachusetts became the first person to have a broken bone set with their help. The new technology quickly found its way into scientific research, exploding into experimental significance following the 1912 development of X-ray crystallography, which offered a first-time look into the atomic-scale arrangement of crystals. Having exposed crystals to X-ray beams, the father-son team of Henry and Lawrence Bragg, found that the beams diffracted off the crystal’s atoms, and could be captured on film to disclose the crystal structure.
X-ray crystallography has since contributed to the discovery of DNA’s double-helix structure, drug development and far more. Today, sophisticated computational methods are applied to analyzing crystal diffraction patterns.
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Studies of how crystals form may weave together a web of unrelated fields, from those targeting semiconductor technologies, to studies of the origin of life, to the design of polymorphs—crystal formations of key importance in pharmacology.
The common denominator is size. To study these research challenges, Institute scientists apply X-rays to view as well as control the growth of crystals at the atomic level.
Profs. Meir Lahav and Leslie Leiserowitz of the Institute’s Department of Materials and Interfaces pioneered the use of grazing incidence X-ray diffraction (GIXD) to analyze the structure of nanosized crystallites formed at the interface between air and water. The investigators are able to work out the exact structure of the crystals formed, according to the way the beam diffracts.
In their analyses, the team has yielded insights into a list of riddles, including how cholesterol crystals form in the body, causing heart disease and gallstones when in excess; the fundamental mechanisms of how water freezes; and the possible routes by which biological molecules such as proteins were first formed. The approach was developed in collaboration with a team of Danish physicists.
The team is currently studying how to control the design and growth of polymorphs—crystals that have different shapes despite being made from the same compound. Polymorphs are of keen interest to the pharmaceutical industry due to their potential influence on drug efficacy. For instance, penicillin crystallized into a form that easily dissolves in the body may be more potent than a penicillin drug packaged in a less soluble crystal. Polymorphs also feature prominently in the production of nanoscopic films used in semiconductors.
