Optical absorption spectrum of excited Cr3+ ions in yttrium aluminum garnet

An investigation was made of the absorption spectrum of Cr³⁺ ions in the ground (⁴A₂) and metastable (²E) states, and of the luminescence spectrum of the same ions in Y₃Al₅O₁₂ crystals at 300 and 77°K. The effective absorption cross sections were determined for the ⁴A₂ state. The luminescence deexcitation time was found to be 1.5 and 9 msec at 300 and 77°K, respectively. The absorption spectrum of the ²E state had four wide absorption bands with maxima at 16,700, 23,300, 28,600, and 40,500 cm^–1. The theoretical energy level scheme of Cr³⁺ was calculated for Dq = 1725 cm^–1, G = 640 cm^–1, C = 3200 cm^–1, v = 495 cm^–1, and v' = 259 cm^–1, making an allowance for the mixing of the Γ^trigS states. The experimentally observed absorption bands were attributed to specific transitions and the theoretical and experimental intensities were compared.