Probing high energy levels of lanthanide ions - experiment and theory

Abstract

This thesis describes vacuum ultraviolet (VUV) spectroscopy of lanthanide ions. High-resolution emission and excitation spectra were recorded to investigate the VUV energy levels of lanthanide ions in fluoride and phosphate host lattices. A parameterized model for the calculation of the energy-level structure is presented. By combining experimentally observed energy levels and calculated energies, it is possible to perform a least squares fit in order to optimize the parameter values. The newly obtained parameter values can be used to perform more accurate energy-level calculations.

Using synchrotron radiation many previously unobserved energy levels of the holmium ion were found.

One- and two-photon techniques are used to probe the VUV levels of trivalent gadolinium ions in LaF3.

The computer program based on the calculation model is also used to simulate emission spectra. The experimentally observed high resolution 4fn-15d→ 4fn emission spectra of Ce3+, Pr3+, Nd3+, Er3+ and Tm3+ in LiYF4 and YPO4 are well reproduced by the calculated spectra.

Tm3+ was investigated as a sensitizer for the Gd/Eu quantum cutting couple. Unfortunately Tm ions were found to interfere with the quantum cutting process.

Finally, the maximum visible quantum effciency of a qauntum cutter based on erbium ions was calculated using Judd-Ofelt theory.