Observation of double-resonant laser-induced transitions in the v=n-l-1=2 metastable cascade of antiprotonic He-4 atoms

Another laser-induced resonant transition in the upsilon=n-l-1=2 metastable cascade of antiprotonic He-4 atoms has been found by using a double-resonance technique. This was done by setting the first laser to the already known 470.724-nm resonance [(n,l)=(37,34)-->(36,33)], while the (38,35)-->(37,34) transition was searched for with the second laser. The resonant transition was found at a wavelength of 529.622+/-0.003 nm, showing excellent agreement with a recent prediction of Korobov.