Astronomical Detection
H3+ has been detected in two types of celestial environments: Jovian planets and interstellar clouds. In Jovian planets, it has been detected in the planet’s ionospheres, the region where the Sun’s high energy radiation ionizes the particles in the atmosphere. Since there is a high level of H2 in these atmospheres, this radiation can produce a significant amount of H3+. Also, with a broadband source like the Sun, there is plenty of radiation to pump the H3+ to higher energy states from which it can relax by stimulated and spontaneous emission.
Read more about this topic: Trihydrogen Cation