Higher Energy Levels of Cr3+ Ion Pairs in Ruby and Lanthanum Aluminate

The excitation and absorption spectra were investigated of the doubly excited states |2E × 2E〉, |2E × 2T1〉, |2T1 × 2T1〉 × 2T1, and |2E×2T2 of the first nearest neighbour Cr3+ ion pairs in LaAlO3, and of the first, second, third, and fourth nearest neighbour Cr3+ pairs in ruby. The spectra were analyzed for electronic and vibronic transitions.