Astrophysics and Space Physics: Figure 4

Grotrian diagram for the Bowen fluorescence mechanism. The observed fluorescence occurs when the emission from the HeII Lyman-alpha transition pumps the 2p P state of OIII to the state 2p3d P. This leads to the enhanced emission from the transition down to the states 2p3p P, S, and D. There is also enhanced emission from these states to the 2p3s P level. In addition, it has been pointed out that the emission from the OIII 2p3s P to the 2p P can pump the ground state of NIII 2p P to the 2d D level, which then can decay via the 3p P level with enhanced emission in the visible. This latter part of the mechanism is not yet confirmed. The NIF would be required in order to generate both the large volumes of plasma necessary and a radiation source sufficient to create the plasma in an appropriate state to provide experimental verification of the Bowen mechanism.