RESUMEN
Molybdenum disulfide has been prepared in an unusual poorly crystalline form, termed the "rag" structure, consisting of several stacked but highly folded and disordered S-Mo-S layers. This previously unknown structure demonstrates the flexible and macromolecular nature of the layered transition metal dichalcogenides. The determination of this structure provides a basis for understanding its highly broadened x-ray diffraction pattern and relatively low surface area, and is a starting point for optimizing the catalytic and surface properties of molybdenum disulfide.
RESUMEN
The remote sensing of laser-induced uranyl ion fluorescence is examined as a potential indicator of uranium occurring in geologic materials at the earth's surface. The lifetime and brightness of the fluorescence from a wide variety of rocks, minerals, and soils are reported. The distinctive characteristics of uranyl ion absorption and fluorescence were observed in diverse geologic materials such as chalcedonies and opals containing 15-3000 ppm of uranium and in surface coatings of uranyl minerals such as metaautunite, liebigite, and an-dersonite. The conditions which permit the excitation and selective detection of uranyl ion fluorescence from such targets are described.
RESUMEN
An analysis is presented of a method to detect selectively uranyl ion fluorescence from geologic targets. Limitations to the sensitivity which are imposed by system parameters and noise sources are discussed. A ground-based laser system designed and constructed as part of this study is described, and data obtained with this system are presented. Finally the operating criteria of a conceptual airborne system for regional mapping of uranyl fluorescence anomalies are considered.