Abstract
The optical transitions in : from the lowest 5d excited state of the ion to the host conduction band have been investigated. Two spatially overlapped and time-sequenced laser pulses were used to observe directly the excited-state absorption (ESA) and the two-step photoionization of the cerium ions. The peak cross section of the ESA transition is (1.0±0.3)× at 700 nm. The ESA spectrum was measured from 600 to 880 nm and is used to construct an energy-level diagram for the ions relative to the energy-band states of the host. The energy gap between the lowest relaxed 5d state and the conduction-band edge is estimated to be 10 000 . Strong-probe saturation measurements indicate a slow and inefficient back-transfer of excitation to the cerium ions following the ESA. Photoconductivity measurements were used to confirm the two-step photoionization of the cerium ions.
- Received 5 December 1988
DOI:https://doi.org/10.1103/PhysRevB.39.8807
©1989 American Physical Society