From investigating new sources of clean and renewable energy to assisting in the search for one of nature’s most elusive particles, scientists in the Chemistry Department have a long history of research and an even brighter future. Below is just a glimpse of the department’s accomplishments and current projects.
Searching for Neutrinos
Solar neutrinos – uncharged, elementary particles produced in the nuclear reactions that power the sun – have long been sought after by Brookhaven chemists. Because neutrinos interact with matter very rarely, large detectors, usually filled chemically laced liquid, are needed to catch the elusive particles. In the late 1940s, using a 1,000-gallon tank of carbon tetrachloride, Brookhaven researchers attempted to study neutrinos emitted from reactors, in particular, the Lab’s Graphite Research Reactor. Next, the scientists turned their focus to neutrinos produced by the sun. Using 100,000 gallons of perchloroethylene (inset), Brookhaven chemists initiated and operated the pioneering experiments that uncovered the famous solar neutrino deficit, a puzzling discovery that the number of solar neutrinos detected on Earth is only a fraction of that predicted by theory. This experiment, conducted in Lead, South Dakota in the early 1970s, led to the 2002 Nobel Prize in Physics for Brookhaven chemist Raymond Davis, Jr. More...
Following this discovery, Brookhaven’s Solar Neutrino Group participated in two major solar neutrino experiments that elucidated the nature of the “solar neutrino problem”: from 1986-1998 in GALLEX in Gran Sasso, Italy, and from 1996 to 2006 in the Canadian Solar Neutrino Observatory (SNO). Both of these experiments depended on vast amounts of chemically prepared liquid for its detectors – 30 tons of gallium for GALLEX and 1,000 tons of heavy water for SNO – which Brookhaven chemists helped test and purify. SNO eventually “solved” the neutrino problem some 30 years after its discovery by demonstrating that two-thirds of the neutrinos emitted by the Sun "disappear" by morphing, or oscillating, among three varieties of neutrinos as they journey to the Earth. The presence of these oscillations proves that neutrinos have mass, and this provides the first solid experimental evidence that the Standard Model, which describes the interactions among subatomic particles, needs to be extended.
Now, scientists are studying these oscillations in detail. At the proposed Daya Bay Neutrino Project in southern China, Brookhaven scientists are part of an international team trying to find a specific neutrino oscillation quantity as the particles are emitted from a series of nuclear reactors. This could help scientists understand more about neutrino behavior, the extension of the Standard Model, and possibly the early history of the universe.
Imaging and Neuroscience
While most other imaging methods reveal structure, Positron Emission Tomography (PET) is a widely used technique to probe brain function. PET images are developed by reconstructing the locations at which positrons (particles with the opposite charge of electrons) are annihilated after being emitted from radioactive compounds metabolized in the brain. In addition to its groundbreaking PET studies of the mechanisms of addiction and treatment of addiction, Brookhaven chemists played an important role in the method used for the discovery and synthesis of radiopharmaceuticals. The synthesis and use of a radioactive compound called fluorodeoxyglucose (FDG) was pioneered by researchers in the Chemistry Department, and FDG is now the most popular compound used in PET studies worldwide.
The Positron Emission Tomography Group and the Magnetic Resonance Imaging (MRI) Group, formerly in the Chemistry Department, along with the PET, MRI, and Imaging groups in the Brookhaven Medical Department now comprise the Brookhaven Center for Translational Neuroimaging, an interdisciplinary organization that reflects the diverse nature of modern medical imaging.
Investigating Alternative Fuels
One way to develop alternative, cost-effective, and clean fuels involves the use of solar energy. Specifically, Brookhaven chemists want to design a system inspired by photosynthesis, the natural process by which green plants convert sunlight, water, and carbon dioxide into oxygen and carbohydrates. The groundwork for this research was laid in the late 1950s, as BNL scientists investigated electron transfer, the process in which the overall energy in a system of interacting molecules changes and induces an electron to jump from one molecule to another, and drives complex reactions such as photosynthesis. This led to research today on so-called “artificial photosynthesis,” in which man-made systems produce fuels like methanol, methane, and hydrogen directly from water and carbon dioxide using renewable solar energy. More...
In their attempts to create these photosynthetic systems, Brookhaven chemists also are learning how to split water, in which one of the products is hydrogen. Hydrogen has great potential as a clean replacement for petroleum, but storing it safely and compactly is difficult. In 1965, Brookhaven chemists discovered an iron-titanium hydride with great potential as a safe means of storing hydrogen. Today, BNL researchers are looking at aluminum hydride as a potential hydrogen storage material as well as the use of different catalysts for fuel cell reactions and hydrogen production.
Related to this effort, researchers have demonstrated new catalysts that reduce the amount of platinum used in fuel cells, making the technology much more cost-effective. BNL scientists also have discovered that adding gold clusters to the system can slow the deterioration of platinum electrocatalysts and make fuel-cell powered electric cars more feasible. More...