University of Iowa physicists have successfully measured the movement history of particles in an ionized gas increasingly used in the high-tech industry.

Plasma is an ionized gas used in making many microelectronic or electronic devices, such as semiconductors. It also can help make features on chips for computers and has been used to manufacture transmitters for microwave ovens or high-temperature films.

But one obstacle to increasing the use of plasma is fully understanding the movement of particles, such as ions, which are used for many of the industrial applications. In a study published in Physical Review Letters, Feng Chu, post-doctoral researcher in the Department of Physics and Astronomy, measured the quantum-state history of individual particles and then used that information to track the movement of entire groups.

Chu, working with paper co-author Fred Skiff, professor and chair in the Department of Physics and Astronomy, employed laser-induced fluorescence to determine how individual particles changed from one quantum state to another. He then used radio waves to slightly change the particle motions, which allowed him to determine their movement history.

“In our paper, we report an experiment in benchmarking the lifetime and history of metastable ions in a plasma for the first time,” Chu says. “This new technique addressed in the paper will greatly help people who adopt laser-induced fluorescence in their experiments in the future.”

The paper is titled “Determining metastable ion lifetime and history through wave-particle interaction.”

The U.S. Department of Energy funded the research.