Scientists from Tokyo Metropolitan University have found a way to make plasma more effective for its wide-ranging uses, from antimicrobial applications to surface conditioning in the semiconductor industry. They mapped the production of atomic oxygen, a key ingredient of oxygen plasma, while a high voltage was applied across oxygen gas.

They discovered that the amount of atomic oxygen available for reactions increased at pressures moderately lower than atmospheric pressure. Their findings promise more energy-efficient, higher-performance plasma technologies.

Plasma is often called the fourth state of matter, alongside gas, liquid and solid. Made of charged atoms and electrons, plasma makes up an estimated 99.9% of all matter in the universe. Although it is rarely encountered on Earth except during lightning storms, artificial plasmas can be generated by applying high electrical voltages across gases, creating so-called nonthermal plasmas. In these plasmas, only the electrons are driven to a high temperature, leaving the atoms in a highly reactive “radical” state.