A team from the Research School of Physics and Engineering have accurately measured the lifespan of the longest-lived excitable atom for the first time.

Physicist Professor Ken Baldwin said the find, published in the journal Physical Review Letters, was a culmination of more than a year of work by the team.

They determined that when helium atoms are energised by a high velocity electron collision, they remain excited for more than 8000 seconds, or over two hours.

''Excited atoms, which are also known as metastable atoms, are an important source of stored energy in ionised gases that occur in the Earth and planetary atmospheres, as well as in lighting and laser technologies,'' he said.

''It's this kind of ionised gas, or plasma, that's inside the compact fluorescent light bulbs and other fluorescent lights around your house.

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