Nuclear Chemistry Research at Washington Univeristy

The Department of Chemistry at Washington University has had a long history of contributions to the area of nuclear chemistry. In the late 1940's, Professors Art Wahl and Joseph Kennedy joined the department. They, along with Glenn Seaborg, discovered the element plutonium in 1940. Two scientists in our department, Professor Lee Sobotka and Professor Demetrios Sarantites, continue this tradition of nuclear chemistry.

In some ways there are parallels between the behavior of nuclear matter and regular liquid droplets. Just like liquid droplets, nuclei can be deformed and broken into smaller droplets. Also, like common liquids, nuclei are fairly incompressible (this means that even if their shapes change, their density does not change). Of course, there are many differences as well. For instance, in one of the example problems in this tutorial you calculated the density of nuclear matter, which is huge compared to any fluid you have ever seen.

Many of the experiments carried out by researchers in this field involve accelerating a beam of projectile nuclei to extremely high velocities (> 1% of the speed of light) and monitoring the results of the beam's collision with target nuclei to determine the types of nuclei and smaller fission particles that are produced (and the energies and momenta of the products). This type of nuclear collision process is depicted in the figure below.

The data in the figure below, from one of Professor Sobotka's published studies, shows the type of nuclei produced from one such nuclear bombardment. The x-axis provides a measure of the masses of the product nuclei and the y-axis indicates the relative number of each of these isotopes produced in the process. The data in the top two figures was gathered using one type of detector and that in the bottom row was gathered using another kind of detector.

Figure from: Nuclear Instruments and Methods in Physics Research A, vol. 473: pages 302-318 (2001).

Studying the behavior of nuclear matter is important for understanding the behavior of neutron stars and the formation of the elements (called nucleosynthesis). The process of nuclear fragmentation shown above (called fission) releases incredible amounts of energy. In the next tutorial on atomic masses we will see how to calculate the amount of energy released via such processes.

Application Question: Refer to the figure above. How many protons and neutrons are in the nuclei of each of the carbon isotopes produced in the nuclear decay process? How many neutrons are in the most abundant oxygen isotope? Answer

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