Upconversion phenomena in the Yb3+ doped transition metal compounds Rb2MnCl4 and CsMnBr3

Abstract Crystals of Yb 3+ doped Rb 2 MnCl 4 and CsMnBr 3 show orange–red Mn 2+ 4 T 1 g → 6 A 1 g upconverted luminescence under near-infrared Yb 3+ excitation. By short 10 ns pulse excitations the upconversion (UC) process for both compounds has been determined to consist of a sequence of ground and excited-state absorption steps. This mechanism can gain nonzero probability by assuming an exchange mechanism between Yb 3+ and Mn 2+ . The efficiency of the UC process is dependent on the structural nature of the Yb 3+ –Mn 2+ connection. It is three orders of magnitude more efficient in Rb 2 MnCl 4 : Yb 3+ with a corner-sharing Yb 3+ –Cl–Mn 2+ arrangement than in the face-sharing Yb 3+ –Br 3 –Mn 2+ arrangement of CsMnBr 3 : Yb 3+ .