Abstract
The luminescence efficiency of isolated $F$ centers in KI was studied as a function of the excitation energy by measuring the lifetime for ordinary luminescence. The emission intensity measured under a pulse excitation was found to obey nonexponential decay. The luminescence efficiency decreases to below unity when the excitation energy exceeds 1.96 eV, which corresponds to the slope position at the higher energy side of an $F$ absorption band. The threshold value for the luminescence efficiency is lower than that previously obtained from cw measurements but close to that predicted theoretically by Leung and Song. We have traced the origin of this difference by performing experiments based on the cw method and found out the reason. It is shown that there is a relationship between quantities obtained by the cw method and those obtained by our lifetime measurement. Our experimental data are thoroughly analyzed using a model for the radiationless process of Leung and Song, which is based on a $1s\text{\ensuremath{-}}2p$ model. A $1s\text{\ensuremath{-}}2p\text{\ensuremath{-}}2s$ model is also discussed.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
