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Optical absorption and electron paramagnetic resonance (EPR) techniques have been used to characterize the production and thermal decay of point defects in undoped single crystals of KD2PO4 grown at Lawrence Livermore National Laboratory. All the electron and hole traps reported are expected to participate in the room-temperature response of KD2PO4 crystals to pulsed high-power ultraviolet laser beams.

The results of an electron paramagnetic resonance (EPR) investigation of a new hole trap and several new electron traps in undoped potassium dihydrogen phosphate (KDP) crystals are discussed. An angular study of the EPR spectra, conducted at room temperature, provide principal values and directions for the g matrices and hyperfine matrices for the hole center and two of the electron centers.

A new Ti3+ center in potassium titanyl phosphate has been identified using electron paramagnetic resonance and electron nuclear double resonance.

The results are described of an electron paramagnetic resonance investigation into three platinum centres induced in potassium titanyl phosphate by ionizing radiation.

Defect-related optical absorption in zinc germanium diphosphide characterization was undertaken.

The role of silicon impurities as hole traps in KTiOPO4 crystals is investigated using electron paramagnetic resonance. This center is formed when crystals are exposed to either 60 kV x rays or pulsed 355 laser beam. It is shown that the silicon-associated hole centers decay at room temperature due to the release of electrons from the Ti(super 3+) centers. The kinetics of the electron-release process are also second-order. A theoretical model for the hole center is derived.

Flux-and hydrothermally-grown potassium titanyl phosphate (KTP) crystals induce variations in the local environmental of Ti(3+) centers developed in the crystals. Ti(3+) centers in flux-grown KTP lack a neighboring proton near hydrothermally-grown Ti(3+) centers. These variations account for the varying susceptibilities of the KTP crystals to gray tracking.

The properties of point defects in single crystals of lithium triborate are investigated using electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR), optical absorption and thermoluminescence (TL). Magnetic resonance data for both the EPR and ENDOR spectra are obtained by means of a Bruker Model ESP300 spectrometer. The TL data are taken using an RCA photomultiplier. The spectra are then irradiated with 60 kilovolts x-rays. Results show that the EPR spectra exhibits two point defects, one holelike and the other electron-like.

Electron-paramagnetic-resonance (EPR) studies at 17k of single crystals of as-grown CdGeAs2 reveal the presence of several paramagnetic point defects. Broad and sharp spectral signals observed correspond to an unpaired-spin concentration of nearly 5 times ten to the 19th power per cubic cm. Either a cation valency or an antisite cation with an unpaired spin common to four adjacent As ions is present in the dominant EPR-active defects.

A study related to an electron paramagnetic resonance (EPR) spectrum from [Er.sup.3+] ions observed in a bulk single crystal of aluminum nitride (AlN) is reported. The [Er.sup.3+] EPR signal monitored at 4.5 K exhibited axial symmetry and showed well-resolved hyperfine splittings due to [super 167] Er nuclei.

The oxygen vacancies and zinc vacancies in ZnO crystal irradiated near room temperature with 1.5 MeV electrons were monitored by employing electron paramagnetic resonance (EPR). The results demonstrated the interrelated behavior of zinc vacancies, oxygen vacancies, and iron impurity ions when the irradiated crystal is illuminated at low temperature.

An electron paramagnetic resonance (EPR) is used to study the photoinduced changes in charge states of transition-metal impurities in a hydrothermally grown ZnO crystal. The results have shown that the isolated zinc vacancies and oxygen vacancies are not present in measurable concentrations in as-grown hydrothermal crystals.

An intense infrared absorption band is observed in a hydrothermally grown ZnO crystal. The result of the observance illustrates the role of hydrogen as a charge compensator for singly ionized acceptors in ZnO.

Electron paramagnetic resonance (EPR) was used to investigate chromium ions in a single crystal of CdGeAs2 grown by the horizontal gradient freeze method. Results suggest that growth conditions and stoichiometry may play a significant role in deterring the amount of Cr incorporated on each action site.

The point defects in single crystals of beta-BaB2O4 (commonly referred to as BBO) are investigated to study the electron paramagnetic resonance (EPR). The role of electron and hole traps in the response of BBO crystals to high-power pulsed ultraviolet lasers is highlighted.

Electron paramagnetic resonance (EPR) is used to investigate molecular nitrogen and isolated nitrogen acceptors in single crystals of ZnO. These samples when grown by the seeded chemical vapor transport method with N2 added to the gas stream, arise from nearly equal hyperfine interactions with two nitrogen nuclei.

Thermally stimulated luminescence (TSL) results obtained form stoichiometric LiTaO3 is described. The crystals were grown from a congruent melt and made stoichiometric by a post growth vapor transport-equilibration (VTE).

The point defects in Mg-doped stoichiometric LiNbO3 are characterized by using the thermoluminescence (TL), optical absorption, and electron paramagnetic resonance (EPR). When these crystals are irradiated at 77 K and then rapidly warmed, a broad TL emission was observed near 94 K.

The role of silicon impurities as dominant hole trap in nominally undoped Czochralski-grown yttrium-orthovanadate (YVO4) crystals is characterized by using the electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR). It was seen that the trapped-hole center appeared in large concentrations in all the YVO4 crystals that were exposed to ionizing radiation while the crystal was at 77 K and a small concentration of trapped-hole center was seen in some YVO4 crystals before they were exposed to ionizing radiation.