Study on argon metastable and 4p state neutral atoms in magnetized ICP and Helicon plasmas measured by Laser Induced Fluorescence and plasma emission

The energy levels from which electric dipole radiation is forbidden are called metastable. An atom or molecule in metastable state can have much longer life-time than typical excited species which decay via electric dipole radiation. Moreover, metastable levels are highly excited above the ground state so that metastable species can act as an energy reservoir. Because of these unusual properties, metastable species have been an interest in various fields such as geophysics, gas discharge lasers, and material processing plasmas.