Showing 1–3 of 3 results for author: Berden, G

The observation of electron trap liberation in MgF$_{2}$ doped with Yb$^{2+}$ using a two-color excitation experiment

Authors: P. S. Senanayake, J. P. R. Wells, M. F. Reid, G. Berden, A. Meijerink, R. J. Reeves

Abstract: We utilize the optical transitions of Yb$^{2+}$ excited by an ultraviolet optical parametric amplifier to probe electron trap liberation in MgF$_{2}$ via the observation of a photoluminescence enhancement effect induced by a subsequent infrared pulse from a free-electron laser. The temperature dependence of the enhancement suggests that we liberate very shallow traps having a depth of approximatel… ▽ More We utilize the optical transitions of Yb$^{2+}$ excited by an ultraviolet optical parametric amplifier to probe electron trap liberation in MgF$_{2}$ via the observation of a photoluminescence enhancement effect induced by a subsequent infrared pulse from a free-electron laser. The temperature dependence of the enhancement suggests that we liberate very shallow traps having a depth of approximately 17 cm$^{-1}$. The observed `trap spectrum' is consistent with a simple model of a Coulomb trap. △ Less

Submitted 30 October, 2011; originally announced October 2011.

Impurity-trapped excitons and electron traps in CaF$_2$:Yb$^{2+}$ and SrF$_2$:Yb$^{2+}$ probed by transient photoluminescence enhancement

Authors: P. S. Senanayake, J. P. R. Wells, M. F. Reid, G. Berden, A. Meijerink, R. J. Reeves

Abstract: CaF$_2$:Yb$^{2+}$ and SrF$_2$:Yb$^{2+}$ crystals have been investigated by a two-color UV + IR transient photoluminescence enhancement technique. The enhancement gives information about both changes in internal energy levels of the excitons and liberation of electrons from traps in the crystals. CaF$_2$:Yb$^{2+}$ and SrF$_2$:Yb$^{2+}$ crystals have been investigated by a two-color UV + IR transient photoluminescence enhancement technique. The enhancement gives information about both changes in internal energy levels of the excitons and liberation of electrons from traps in the crystals. △ Less

Submitted 6 October, 2011; v1 submitted 25 July, 2011; originally announced July 2011.

Comments: Minor updates and add DOI

Transient photoluminescence enhancement as a probe of the structure of impurity-trapped excitons in CaF$_2$:Yb$^{2+}$

Authors: Michael F. Reid, Pubudu S. Senanayake, Jon-Paul R. Wells, Giel Berden, Andries Meijerink, Alexander J. Salkeld, Chang-Kui Duan, Roger J. Reeves

Abstract: We demonstrate a direct measurement of the energy levels of impurity-trapped excitons in CaF$_2$:Yb$^{2+}$. The radically different radiative decay rates of the lowest exciton state and higher excited states enable the generation of a transient photoluminescence enhancement measured via a two-step excitation process. We observe sharp transitions arising from changes of state of localized electrons… ▽ More We demonstrate a direct measurement of the energy levels of impurity-trapped excitons in CaF$_2$:Yb$^{2+}$. The radically different radiative decay rates of the lowest exciton state and higher excited states enable the generation of a transient photoluminescence enhancement measured via a two-step excitation process. We observe sharp transitions arising from changes of state of localized electrons, broad bands associated with changes of state of delocalized electrons, and broad bands arising from trap liberation. △ Less

Submitted 23 September, 2011; v1 submitted 15 July, 2011; originally announced July 2011.

Comments: Minor corrections. arXiv admin note: text overlap with arXiv:1107.4888v2

Journal ref: Phys. Rev. B 84, 113110 (2011) [4 pages]