Disorder-to-order transition of 1,4-dimethylnaphthalene: Formation of molecular complex with water and p-xylene on Al2O3 (0001).

Amorphous 1,4-dimethylnaphthalene, DMN, that can be prepared by vacuum deposition on Al2O3 exhibits relatively intense excimer fluorescence. Upon heating the surface, the adlayer undergoes a disorder-to-order transition, signaled by a decrease in excimer and an increase in monomer fluorescence. In a bilayer experiment, water, which has a lower desorption temperature than DMN, is vacuum deposited first, followed by DMN. When the surface is heated, water percolates through the DMN and forms a molecular H2O-DMN surface complex that desorbs simultaneously. The stoichiometric ratio of this complex was determined to be (DMN)(1.4+/-0.3).H2O. When the bilayer was formed with p-xylene, a complex of DMN-p-xylene was observed that had the stoichiometry of (DMN)(7.9+/-1).p-xylene.

Diffuse edge fitting and following: a location-adaptive approach.

The detection and tracing of edges of varying diffusion is a problem of importance in image analysis. In particular, it is of interest for the segmentation of meteorological and physiological pictures where the boundaries of objects are possibly not well defined or are obscured to a varying extent by noise. We present an edge detection and line fitting procedure which ascribes a direction, a measure of gradient, and quality of fit to the edge within a square segment of a controlled size or ``scope.'' To detect and fit edges to diffuse objects the scope is adaptively altered based on the confidence of fit to permit tracing of the object's boundary. We discuss predictor-corrector procedures for performing this edge tracing where predicted and calculated lines and confidences are used to generate a better fitting line. The performance of the procedures is demonstrated using both synthetic and satellite meteorological images.