Resonantly photo-pumped Li-like x-ray lasers.

We identify potential candidates for achieving x-ray lasing in Li-like ions by utilizing Ly-alpha or He-alpha radiation to photopump an electron resonantly from the n = 2 state of the Li-like ion to the n = 4 or 5 state with subsequent lasing between the n = 5 ? n = 4, n = 5 ? n = 3, or n = 4 ? n = 3 states of the Li-like ion. To identify potential resonances we calculate all the n = 2 ? n = 4 and 5 transitions in Li-like ions that look favorable to pump and identify the resonances that are possible with Ly-alpha or He-alpha radiation. Many laser candidates are identified with the baron-pumped Na scheme being modeled as it appears to be an extremely promising candidate that could be driven by pulsed power machines or optical lasers of modest energy. Since gain has already been observed in Li-like ions because of recombination one can also combine the advantages of resonant photopumping with recombination to produce an improved Li-like laser.