Investigation of piezoelectric ringing effects in Pockels cells based on beta barium borate crystals.

A detailed investigation of piezoelectric ringing and resonance effects in beta barium borate (BBO)-crystal-based Pockels cells in a pulse picker device is presented. Measurements mapping piezoelectric oscillation amplitude distribution in the aperture of BBO crystal are also performed. It is determined that in BBO Pockels cells, due to piezoelectric ringing and related effects, the optical contrast ratio is reduced by six to 70 times at certain (resonance) frequencies.

Pulsed photo-ionization spectroscopy of traps in as-grown and neutron irradiated ammonothermally synthesized GaN.

GaN-based structures are promising for production of radiation detectors and high-voltage high-frequency devices. Particle detectors made of GaN are beneficial as devices simultaneously generating of the optical and electrical signals. Photon-electron coupling cross-section is a parameter which relates radiation absorption and emission characteristics.

Spike threshold dynamics in spinal motoneurons during scratching and swimming.

Key Points: Action potential threshold can vary depending on firing history and synaptic inputs. We used an ex vivo carapace-spinal cord preparation from adult turtles to study spike threshold dynamics in motoneurons during two distinct types of functional motor behaviour - fictive scratching and fictive swimming. The threshold potential depolarizes by about 10 mV within each burst of spikes generated during scratch and swim network activity and recovers between bursts to a slightly depolarized level.

The influence of increased membrane conductance on response properties of spinal motoneurons.

During functional spinal neural network activity motoneurons receive massive synaptic excitation and inhibition, and their membrane conductance increases considerably - they are switched to a high-conductance state. High-conductance states can substantially alter response properties of motoneurons. In the present study we investigated how an increase in membrane conductance affects spike frequency adaptation, the gain (i.

Cation influence on exciton localization in homologue scheelites.

Homologue scheelite crystals CaWO4, SrWO4, and BaWO4 possess similar crystal and electronic structure, but their luminescence exhibits drastically different thermal stabilities. By measuring the temperature dependence of the decay time of the intrinsic luminescence and fitting it to a three level model, we have qualitatively shown the effective exciton radius to increase in the order CaWO4 → SrWO4 → BaWO4, which explains the differences in the thermal stability. The origin of the variation in the exciton radii is suggested to be related to differences in the excited state dynamics in these crystals.