In this study, we use electron paramagnetic resonance (EPR), optical absorption, and photoluminescence (PL) spectroscopies to determine the various Ce environments in SrS phosphor materials and how these affect absorption and emission properties. As the Ce concentration is increased from 450 to 7500 ppm, the total EPR-active Ce3+ and optical absorption signals increase linearly with Ce concentration; by contrast, the PL intensity saturates at fairly low Ce concentrations (1000 ppm Ce). We suggest that the nonlinear behavior of the PL arises from the presence of nonradiative deexcitation pathways such as defects associated with Ce sites, or Ce–Ce pairs.

The determination of thin film thickness by four X-ray reflectivity methods (namely, the peak separation, the Fourier transform, the modified Bragg equation, and the curve-fitting methods) has been studied. An analysis of SrS and BaF2 thin films showed thickness values determined by the methods agreed to within 4%. The curve-fitting method had the highest accuracy but was time-consuming. The peak separation, the Fourier transform, and the modified Bragg equation methods are considerably faster and, on average, gave 2.8%, 0.9%, and 0.2% larger thicknesses than those of the curve-fitting method.

The effect of modifying the host composition on the photoluminescent properties of the ir stimulable phosphor system SrBaS : (Eu, Sm) was investigated. Spectral measurements (stimulated emission, fluorescent emission, excitation, and IR stimulation) were made on nine separate host compositions. The lattice constant, ionicity, and lattice strain affect Stark splitting of the rare earth excited states. While large shifts in the ir stimulated emission and fluorescence wavelengths were observed, no shift was observed for the peak excitation and ir stimulation wavelengths.

Stimulable phosphor thin films are being investigated for use as optical data storage media. We have successfully applied atomic force microscopy (AFM) to the measurement of the surface texture of these films. Determination of the surface texture of the films is important for evaluating the effect of surface quality on optical scatter. In other thin film material systems it has been found that the surface “bumps” revealed by AFM correspond to grains in the film. This is not the case for the stimulable phosphor films used in our study. We have determined the grain size of our phosphor films by transmission electron microscopy (TEM) and x-ray diffraction (XRD). The grain size from TEM and XRD does not correlate with the size of the AFM surface “bumps.” For example, in two of the five films studied, the XRD derived grain size varies by a factor of two but the size of the surface “bumps” remains the same. We conclude that the texture of the film surface is not directly determined by the grain size of the phosphor material.

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