Vacuum ultraviolet spectroscopy of calcium fluoride crystals
Presented by Mr. Tresor MATINDI on 9 Jul 2014 from 14:40 to 15:00
Type: Oral Presentation
Track: Track C - Photonics
In this project experimental setups and techniques for measuring the absorption and excitation spectra of pure and lead (Pb) doped calcium fluoride (CaF<sub>2</sub>) crystal samples in the vacuum ultraviolet (VUV) spectral range are developed. This study is conducted using tuneable vacuum ultraviolet (VUV) laser light with a narrow spectral bandwidth generated by a 3<sup>rd</sup> order nonlinear optical process. This is the first spectroscopic study of an alkaline fluoride using tuneable VUV laser radiation and therefore of strategic importance. This spectroscopic study should yield a more complete spectral characterization of the doped and pure CaF<sub>2</sub> which will contribute to the understanding of the different types of defects, their energy levels and formation mechanisms. As first step absorption measurements over the spectral range 115-180 nm have been obtain using a vacuum scanning (McPherson model 225) with a deuterium lamp (McPherson model 632). Our results show that total absorption of the VUV light by CaF<sub>2</sub> can be observed in 115-126 nm range. The observed absorption features in the 126-180 nm range vary in different samples and correlate with information from the supplier. In addition, the effect of vacuum and gas purged conditions and the stray light background in the monochromator have been determined.
Dr. Christine M. Steenkamp, Laser Research Institute ,Physics Department, Stellenbosch University