Identification of the intrinsic self-trapped hole center in KD2PO4

The intrinsic "self-trapped" hole center in KD2PO4 crystals has been identi fied using electron paramagnetic resonance and electron-nuclear double reso nance. These defects, labeled [D2PO4](o) centers, can be formed at 77 K by irradiating with either 60 kV x rays or the fourth harmonic (266 nm) of a p ulsed Nd:YAG laser. The hole is equally shared by two adjacent oxygen ions, and hyperfine interactions with one phosphorus and two equivalent deuteron s are observed. The sample used in this investigation was approximately 80% deuterated, thus both [D2PO4](o) and [HDPO4](o) centers were detected, wit h the former being dominant. These intrinsic self-trapped hole centers are of interest because of their potential role in the transient optical absorp tion produced in KD2PO4 crystals at room temperature by intense 266 nm lase r pulses. (C) 1999 American Institute of Physics. [S0003-6951(99)01837-9].